21099510621 has 96 divisors (see below), whose sum is σ = 38357729280. Its totient is φ = 10897286400.

The previous prime is 21099510613. The next prime is 21099510631. The reversal of 21099510621 is 12601599012.

21099510621 is a `hidden beast` number, since 2 + 10 + 9 + 9 + 5 + 10 + 621 = 666.

It is not a de Polignac number, because 21099510621 - 2³ = 21099510613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21099510631) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 14342916 + ... + 14344386.

It is an arithmetic number, because the mean of its divisors is an integer number (399559680).

Almost surely, 2^21099510621 is an apocalyptic number.

21099510621 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21099510621 is a deficient number, since it is larger than the sum of its proper divisors (17258218659).

21099510621 is a wasteful number, since it uses less digits than its factorization.

21099510621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2047 (or 2044 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 36.

The spelling of 21099510621 in words is "twenty-one billion, ninety-nine million, five hundred ten thousand, six hundred twenty-one".