21106170521 has 4 divisors (see below), whose sum is σ = 21106494672. Its totient is φ = 21105846372.

The previous prime is 21106170469. The next prime is 21106170529. The reversal of 21106170521 is 12507160112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21106170521 - 2⁶ = 21106170457 is a prime.

It is a super-2 number, since 2×21106170521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21106170529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26735 + ... + 207188.

It is an arithmetic number, because the mean of its divisors is an integer number (5276623668).

Almost surely, 2^21106170521 is an apocalyptic number.

It is an amenable number.

21106170521 is a deficient number, since it is larger than the sum of its proper divisors (324151).

21106170521 is an equidigital number, since it uses as much as digits as its factorization.

21106170521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 324150.

The product of its (nonzero) digits is 840, while the sum is 26.

The spelling of 21106170521 in words is "twenty-one billion, one hundred six million, one hundred seventy thousand, five hundred twenty-one".