21499135264656 has 675 divisors, whose sum is σ = 74756792376903. Its totient is φ = 5751011589120.

The previous prime is 21499135264619. The next prime is 21499135264703. The reversal of 21499135264656 is 65646253199412.

The square root of 21499135264656 is 4636716.

It is a perfect power (a square), and thus also a powerful number.

21499135264656 is a `hidden beast` number, since 2 + 1 + 4 + 9 + 9 + 13 + 526 + 46 + 56 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6672322951056 + 14826812313600 = 2583084^2 + 3850560^2 .

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 21499135264593 and 21499135264602.

It is an unprimeable number.

It is a polite number, since it can be written in 134 ways as a sum of consecutive naturals, for example, 112560917521 + ... + 112560917711.

Almost surely, 2^{21499135264656} is an apocalyptic number.

21499135264656 is the 4636716-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21499135264656

21499135264656 is an abundant number, since it is smaller than the sum of its proper divisors (53257657112247).

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

21499135264656 is an frugal number, since it uses more digits than its factorization.

21499135264656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478 (or 220 counting only the distinct ones).

The product of its digits is 83980800, while the sum is 63.

The spelling of 21499135264656 in words is "twenty-one trillion, four hundred ninety-nine billion, one hundred thirty-five million, two hundred sixty-four thousand, six hundred fifty-six".