21293131 has 2 divisors, whose sum is σ = 21293132. Its totient is φ = 21293130.

The previous prime is 21293119. The next prime is 21293141. The reversal of 21293131 is 13139212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21293131 - 2⁵ = 21293099 is a prime.

It is a super-2 number, since 2×21293131² = 906794855566322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21293141) 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, 10646565 + 10646566.

It is an arithmetic number, because the mean of its divisors is an integer number (10646566).

Almost surely, 2^21293131 is an apocalyptic number.

21293131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21293131 is an equidigital number, since it uses as much as digits as its factorization.

21293131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 324, while the sum is 22.

The square root of 21293131 is about 4614.4480710048. The cubic root of 21293131 is about 277.1701830574.

The spelling of 21293131 in words is "twenty-one million, two hundred ninety-three thousand, one hundred thirty-one".