21507464163645 has 12 divisors (see below), whose sum is σ = 37279604550396. Its totient is φ = 11470647553920.

The previous prime is 21507464163637. The next prime is 21507464163649. The reversal of 21507464163645 is 54636146470512.

21507464163645 is a `hidden beast` number, since 2 + 1 + 507 + 4 + 64 + 1 + 6 + 36 + 45 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 9271166329881 + 12236297833764 = 3044859^2 + 3498042^2 .

It is not a de Polignac number, because 21507464163645 - 2³ = 21507464163637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21507464163591 and 21507464163600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507464163649) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 238971823996 + ... + 238971824085.

It is an arithmetic number, because the mean of its divisors is an integer number (3106633712533).

Almost surely, 2^{21507464163645} is an apocalyptic number.

It is an amenable number.

21507464163645 is a deficient number, since it is larger than the sum of its proper divisors (15772140386751).

21507464163645 is a wasteful number, since it uses less digits than its factorization.

21507464163645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 477943648092 (or 477943648089 counting only the distinct ones).

The product of its (nonzero) digits is 14515200, while the sum is 54.

The spelling of 21507464163645 in words is "twenty-one trillion, five hundred seven billion, four hundred sixty-four million, one hundred sixty-three thousand, six hundred forty-five".