21103522521 has 12 divisors (see below), whose sum is σ = 29074992336. Its totient is φ = 13615173960.

The previous prime is 21103522519. The next prime is 21103522553. The reversal of 21103522521 is 12522530112.

It is not a de Polignac number, because 21103522521 - 2¹ = 21103522519 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21103522491 and 21103522500.

It is not an unprimeable number, because it can be changed into a prime (21103522571) 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, 3657111 + ... + 3662876.

It is an arithmetic number, because the mean of its divisors is an integer number (2422916028).

Almost surely, 2^21103522521 is an apocalyptic number.

It is an amenable number.

21103522521 is a deficient number, since it is larger than the sum of its proper divisors (7971469815).

21103522521 is an equidigital number, since it uses as much as digits as its factorization.

21103522521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7320052 (or 7320021 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The spelling of 21103522521 in words is "twenty-one billion, one hundred three million, five hundred twenty-two thousand, five hundred twenty-one".