398735640 has 96 divisors (see below), whose sum is σ = 1337731200. Its totient is φ = 102896640.

The previous prime is 398735621. The next prime is 398735647. The reversal of 398735640 is 46537893.

398735640 is a `hidden beast` number, since 3 + 9 + 87 + 3 + 564 + 0 = 666.

It is a super-2 number, since 2×398735640² = 317980221212419200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398735647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6705 + ... + 29024.

It is an arithmetic number, because the mean of its divisors is an integer number (13934700).

Almost surely, 2^398735640 is an apocalyptic number.

398735640 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 398735640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (668865600).

398735640 is an abundant number, since it is smaller than the sum of its proper divisors (938995560).

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

398735640 is a wasteful number, since it uses less digits than its factorization.

398735640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35777 (or 35770 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 45.

The square root of 398735640 is about 19968.3659822230. The cubic root of 398735640 is about 736.0291566506.

The spelling of 398735640 in words is "three hundred ninety-eight million, seven hundred thirty-five thousand, six hundred forty".