400081657 has 4 divisors (see below), whose sum is σ = 400219380. Its totient is φ = 399943936.

The previous prime is 400081639. The next prime is 400081679. The reversal of 400081657 is 756180004.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 206899456 + 193182201 = 14384^2 + 13899^2 .

It is a cyclic number.

It is not a de Polignac number, because 400081657 - 2⁷ = 400081529 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400081637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64408 + ... + 70345.

It is an arithmetic number, because the mean of its divisors is an integer number (100054845).

Almost surely, 2^400081657 is an apocalyptic number.

It is an amenable number.

400081657 is a deficient number, since it is larger than the sum of its proper divisors (137723).

400081657 is a wasteful number, since it uses less digits than its factorization.

400081657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137722.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 400081657 is about 20002.0413208252. The cubic root of 400081657 is about 736.8564341434.

The spelling of 400081657 in words is "four hundred million, eighty-one thousand, six hundred fifty-seven".