21573131 has 2 divisors, whose sum is σ = 21573132. Its totient is φ = 21573130.

The previous prime is 21573127. The next prime is 21573163. The reversal of 21573131 is 13137512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21573131 - 2² = 21573127 is a prime.

It is a super-2 number, since 2×21573131² = 930799962286322, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21573097 and 21573106.

It is not a weakly prime, because it can be changed into another prime (21573121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786565 + 10786566.

It is an arithmetic number, because the mean of its divisors is an integer number (10786566).

Almost surely, 2^21573131 is an apocalyptic number.

21573131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573131 is an equidigital number, since it uses as much as digits as its factorization.

21573131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 630, while the sum is 23.

The square root of 21573131 is about 4644.6884717923. The cubic root of 21573131 is about 278.3798053885.

The spelling of 21573131 in words is "twenty-one million, five hundred seventy-three thousand, one hundred thirty-one".