21242131 has 2 divisors, whose sum is σ = 21242132. Its totient is φ = 21242130.

The previous prime is 21242101. The next prime is 21242153. The reversal of 21242131 is 13124212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21242131 - 2¹³ = 21233939 is a prime.

It is a super-2 number, since 2×21242131² = 902456258842322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21242101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621065 + 10621066.

It is an arithmetic number, because the mean of its divisors is an integer number (10621066).

Almost surely, 2^21242131 is an apocalyptic number.

21242131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242131 is an equidigital number, since it uses as much as digits as its factorization.

21242131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96, while the sum is 16.

The square root of 21242131 is about 4608.9186367303. The cubic root of 21242131 is about 276.9487191494.

Adding to 21242131 its reverse (13124212), we get a palindrome (34366343).

The spelling of 21242131 in words is "twenty-one million, two hundred forty-two thousand, one hundred thirty-one".