21142931 has 2 divisors, whose sum is σ = 21142932. Its totient is φ = 21142930.

The previous prime is 21142907. The next prime is 21142937. The reversal of 21142931 is 13924112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21142931 - 2⁶ = 21142867 is a prime.

It is a super-2 number, since 2×21142931² = 894047062541522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21142897 and 21142906.

It is not a weakly prime, because it can be changed into another prime (21142937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571465 + 10571466.

It is an arithmetic number, because the mean of its divisors is an integer number (10571466).

Almost surely, 2^21142931 is an apocalyptic number.

21142931 is a deficient number, since it is larger than the sum of its proper divisors (1).

21142931 is an equidigital number, since it uses as much as digits as its factorization.

21142931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 23.

The square root of 21142931 is about 4598.1442996061. The cubic root of 21142931 is about 276.5169327354.

The spelling of 21142931 in words is "twenty-one million, one hundred forty-two thousand, nine hundred thirty-one".