401665616640 has 288 divisors, whose sum is σ = 1448729150400. Its totient is φ = 105354362880.

The previous prime is 401665616629. The next prime is 401665616669. The reversal of 401665616640 is 46616566104.

It is a happy number.

401665616640 is a `hidden beast` number, since 40 + 1 + 6 + 6 + 561 + 6 + 6 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×401665616640² (a number of 24 digits) contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2012896 + ... + 2203424.

It is an arithmetic number, because the mean of its divisors is an integer number (5030309550).

Almost surely, 2^401665616640 is an apocalyptic number.

401665616640 is a gapful number since it is divisible by the number (40) 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 401665616640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (724364575200).

401665616640 is an abundant number, since it is smaller than the sum of its proper divisors (1047063533760).

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

401665616640 is a wasteful number, since it uses less digits than its factorization.

401665616640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190620 (or 190600 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 45.

The spelling of 401665616640 in words is "four hundred one billion, six hundred sixty-five million, six hundred sixteen thousand, six hundred forty".