21004688685 has 32 divisors (see below), whose sum is σ = 34091798400. Its totient is φ = 11042220800.

The previous prime is 21004688671. The next prime is 21004688687. The reversal of 21004688685 is 58688640012.

It is a happy number.

It is not a de Polignac number, because 21004688685 - 2⁴ = 21004688669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004688687) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 256915 + ... + 328655.

It is an arithmetic number, because the mean of its divisors is an integer number (1065368700).

Almost surely, 2^21004688685 is an apocalyptic number.

It is an amenable number.

21004688685 is a deficient number, since it is larger than the sum of its proper divisors (13087109715).

21004688685 is a wasteful number, since it uses less digits than its factorization.

21004688685 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72029.

The product of its (nonzero) digits is 737280, while the sum is 48.

The spelling of 21004688685 in words is "twenty-one billion, four million, six hundred eighty-eight thousand, six hundred eighty-five".