21523604164 has 6 divisors (see below), whose sum is σ = 37666307294. Its totient is φ = 10761802080.

The previous prime is 21523604117. The next prime is 21523604183. The reversal of 21523604164 is 46140632512.

It can be written as a sum of positive squares in only one way, i.e., 21158029764 + 365574400 = 145458^2 + 19120^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2690450517 + ... + 2690450524.

Almost surely, 2^21523604164 is an apocalyptic number.

It is an amenable number.

21523604164 is a deficient number, since it is larger than the sum of its proper divisors (16142703130).

21523604164 is a wasteful number, since it uses less digits than its factorization.

21523604164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5380901045 (or 5380901043 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The spelling of 21523604164 in words is "twenty-one billion, five hundred twenty-three million, six hundred four thousand, one hundred sixty-four".