21523564477 has 16 divisors (see below), whose sum is σ = 23309632960. Its totient is φ = 19811164032.

The previous prime is 21523564453. The next prime is 21523564487. The reversal of 21523564477 is 77446532512.

It is a cyclic number.

It is not a de Polignac number, because 21523564477 - 2¹⁵ = 21523531709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523564487) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22878 + ... + 208735.

It is an arithmetic number, because the mean of its divisors is an integer number (1456852060).

Almost surely, 2^21523564477 is an apocalyptic number.

It is an amenable number.

21523564477 is a deficient number, since it is larger than the sum of its proper divisors (1786068483).

21523564477 is a wasteful number, since it uses less digits than its factorization.

21523564477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231772.

The product of its digits is 1411200, while the sum is 46.

The spelling of 21523564477 in words is "twenty-one billion, five hundred twenty-three million, five hundred sixty-four thousand, four hundred seventy-seven".