21687024966489 has 27 divisors (see below), whose sum is σ = 32529450525663. Its totient is φ = 14457765169944.

The previous prime is 21687024966463. The next prime is 21687024966493. The reversal of 21687024966489 is 98466942078612.

The square root of 21687024966489 is 4656933.

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

21687024966489 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 70 + 2 + 496 + 64 + 8 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 8829723105225 + 12857301861264 = 2971485^2 + 3585708^2 .

It is a tau number, because it is divible by the number of its divisors (27).

It is not a de Polignac number, because 21687024966489 - 2²³ = 21687016577881 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21687024966419) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 377182827 + ... + 377240319.

Almost surely, 2^{21687024966489} is an apocalyptic number.

21687024966489 is the 4656933-rd square number.

21687024966489 is the 2328467-th centered octagonal number.

It is an amenable number.

21687024966489 is a deficient number, since it is larger than the sum of its proper divisors (10842425559174).

21687024966489 is an frugal number, since it uses more digits than its factorization.

21687024966489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115010 (or 57496 counting only the distinct ones).

The product of its (nonzero) digits is 501645312, while the sum is 72.

The spelling of 21687024966489 in words is "twenty-one trillion, six hundred eighty-seven billion, twenty-four million, nine hundred sixty-six thousand, four hundred eighty-nine".