1397840640 has 864 divisors, whose sum is σ = 6039774720. Its totient is φ = 272498688.

The previous prime is 1397840627. The next prime is 1397840641. The reversal of 1397840640 is 460487931.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 1397840592 and 1397840601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1397840641) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 60775669 + ... + 60775691.

It is an arithmetic number, because the mean of its divisors is an integer number (6990480).

Almost surely, 2^1397840640 is an apocalyptic number.

1397840640 is a gapful number since it is divisible by the number (10) 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 1397840640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3019887360).

1397840640 is an abundant number, since it is smaller than the sum of its proper divisors (4641934080).

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

1397840640 is a wasteful number, since it uses less digits than its factorization.

1397840640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 76 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 42.

The square root of 1397840640 is about 37387.7070706402. The cubic root of 1397840640 is about 1118.1134908465.

The spelling of 1397840640 in words is "one billion, three hundred ninety-seven million, eight hundred forty thousand, six hundred forty".