21522929 has 4 divisors (see below), whose sum is σ = 21929076. Its totient is φ = 21116784.

The previous prime is 21522923. The next prime is 21522931. The reversal of 21522929 is 92922512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19562929 + 1960000 = 4423^2 + 1400^2 .

It is a cyclic number.

It is not a de Polignac number, because 21522929 - 2⁸ = 21522673 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21522895 and 21522904.

It is not an unprimeable number, because it can be changed into a prime (21522923) 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, 202994 + ... + 203099.

It is an arithmetic number, because the mean of its divisors is an integer number (5482269).

Almost surely, 2^21522929 is an apocalyptic number.

It is an amenable number.

21522929 is a deficient number, since it is larger than the sum of its proper divisors (406147).

21522929 is an equidigital number, since it uses as much as digits as its factorization.

21522929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406146.

The product of its digits is 6480, while the sum is 32.

The square root of 21522929 is about 4639.2810865478. The cubic root of 21522929 is about 278.1637020417.

The spelling of 21522929 in words is "twenty-one million, five hundred twenty-two thousand, nine hundred twenty-nine".