397421640 has 512 divisors, whose sum is σ = 1700352000. Its totient is φ = 81181440.

The previous prime is 397421639. The next prime is 397421641. The reversal of 397421640 is 46124793.

397421640 is a `hidden beast` number, since 3 + 9 + 7 + 4 + 2 + 1 + 640 = 666.

It is an interprime number because it is at equal distance from previous prime (397421639) and next prime (397421641).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 397421595 and 397421604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (397421641) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 6735931 + ... + 6735989.

It is an arithmetic number, because the mean of its divisors is an integer number (3321000).

Almost surely, 2^397421640 is an apocalyptic number.

397421640 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 397421640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (850176000).

397421640 is an abundant number, since it is smaller than the sum of its proper divisors (1302930360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

397421640 is a wasteful number, since it uses less digits than its factorization.

397421640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109 (or 87 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 397421640 is about 19935.4367897972. The cubic root of 397421640 is about 735.2197593600.

The spelling of 397421640 in words is "three hundred ninety-seven million, four hundred twenty-one thousand, six hundred forty".