28400661631 has 4 divisors (see below), whose sum is σ = 28402550064. Its totient is φ = 28398773200.

The previous prime is 28400661617. The next prime is 28400661647. The reversal of 28400661631 is 13616600482.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 28400661631 - 2⁷ = 28400661503 is a prime.

It is a super-2 number, since 2×28400661631² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28400661931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 921475 + ... + 951796.

It is an arithmetic number, because the mean of its divisors is an integer number (7100637516).

Almost surely, 2^28400661631 is an apocalyptic number.

28400661631 is a deficient number, since it is larger than the sum of its proper divisors (1888433).

28400661631 is a wasteful number, since it uses less digits than its factorization.

28400661631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1888432.

The product of its (nonzero) digits is 41472, while the sum is 37.

The spelling of 28400661631 in words is "twenty-eight billion, four hundred million, six hundred sixty-one thousand, six hundred thirty-one".