21315563451 has 96 divisors (see below), whose sum is σ = 40837171200. Its totient is φ = 10880412480.

The previous prime is 21315563449. The next prime is 21315563453. The reversal of 21315563451 is 15436551312.

21315563451 is a `hidden beast` number, since 2 + 1 + 3 + 15 + 5 + 634 + 5 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (21315563449) and next prime (21315563453).

It is not a de Polignac number, because 21315563451 - 2¹ = 21315563449 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21315563453) 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, 513180 + ... + 553158.

It is an arithmetic number, because the mean of its divisors is an integer number (425387200).

Almost surely, 2^21315563451 is an apocalyptic number.

21315563451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21315563451 is a deficient number, since it is larger than the sum of its proper divisors (19521607749).

21315563451 is a wasteful number, since it uses less digits than its factorization.

21315563451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40046 (or 40033 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The spelling of 21315563451 in words is "twenty-one billion, three hundred fifteen million, five hundred sixty-three thousand, four hundred fifty-one".