656401681 has 8 divisors (see below), whose sum is σ = 711577664. Its totient is φ = 601894800.

The previous prime is 656401673. The next prime is 656401687. The reversal of 656401681 is 186104656.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 656401681 - 2³ = 656401673 is a prime.

It is a super-2 number, since 2×656401681² = 861726333639251522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 656401681.

It is not an unprimeable number, because it can be changed into a prime (656401687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 165231 + ... + 169156.

It is an arithmetic number, because the mean of its divisors is an integer number (88947208).

Almost surely, 2^656401681 is an apocalyptic number.

It is an amenable number.

656401681 is a deficient number, since it is larger than the sum of its proper divisors (55175983).

656401681 is a wasteful number, since it uses less digits than its factorization.

656401681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334551.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 656401681 is about 25620.3372538302. The cubic root of 656401681 is about 869.0736080891.

The spelling of 656401681 in words is "six hundred fifty-six million, four hundred one thousand, six hundred eighty-one".