398640644640 has 1008 divisors, whose sum is σ = 1729495696320. Its totient is φ = 86298670080.

The previous prime is 398640644617. The next prime is 398640644653. The reversal of 398640644640 is 46446046893.

It is a happy number.

398640644640 is a `hidden beast` number, since 3 + 9 + 86 + 40 + 64 + 464 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1008).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 167 ways as a sum of consecutive naturals, for example, 108590005 + ... + 108593675.

It is an arithmetic number, because the mean of its divisors is an integer number (1715769540).

Almost surely, 2^398640644640 is an apocalyptic number.

398640644640 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 398640644640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (864747848160).

398640644640 is an abundant number, since it is smaller than the sum of its proper divisors (1330855051680).

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

398640644640 is a wasteful number, since it uses less digits than its factorization.

398640644640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3737 (or 3707 counting only the distinct ones).

The product of its (nonzero) digits is 11943936, while the sum is 54.

The spelling of 398640644640 in words is "three hundred ninety-eight billion, six hundred forty million, six hundred forty-four thousand, six hundred forty".