21171813628 has 36 divisors (see below), whose sum is σ = 44264730160. Its totient is φ = 8679122496.

The previous prime is 21171813557. The next prime is 21171813671. The reversal of 21171813628 is 82631817112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 699873 + ... + 729496.

Almost surely, 2^21171813628 is an apocalyptic number.

21171813628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21171813628 is an abundant number, since it is smaller than the sum of its proper divisors (23092916532).

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

21171813628 is a wasteful number, since it uses less digits than its factorization.

21171813628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429426 (or 1429401 counting only the distinct ones).

The product of its digits is 32256, while the sum is 40.

The spelling of 21171813628 in words is "twenty-one billion, one hundred seventy-one million, eight hundred thirteen thousand, six hundred twenty-eight".