21691185628 has 24 divisors (see below), whose sum is σ = 44440480224. Its totient is φ = 9069484800.

The previous prime is 21691185563. The next prime is 21691185629. The reversal of 21691185628 is 82658119612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691185629) 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, 9446233 + ... + 9448528.

It is an arithmetic number, because the mean of its divisors is an integer number (1851686676).

Almost surely, 2^21691185628 is an apocalyptic number.

21691185628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21691185628 is an abundant number, since it is smaller than the sum of its proper divisors (22749294596).

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

21691185628 is a wasteful number, since it uses less digits than its factorization.

21691185628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18894813 (or 18894811 counting only the distinct ones).

The product of its digits is 414720, while the sum is 49.

The spelling of 21691185628 in words is "twenty-one billion, six hundred ninety-one million, one hundred eighty-five thousand, six hundred twenty-eight".