31521131 has 2 divisors, whose sum is σ = 31521132. Its totient is φ = 31521130.

The previous prime is 31521053. The next prime is 31521143. The reversal of 31521131 is 13112513.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31521131 - 2¹⁴ = 31504747 is a prime.

It is a super-2 number, since 2×31521131² = 1987163399038322, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (31521031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15760565 + 15760566.

It is an arithmetic number, because the mean of its divisors is an integer number (15760566).

Almost surely, 2^31521131 is an apocalyptic number.

31521131 is a deficient number, since it is larger than the sum of its proper divisors (1).

31521131 is an equidigital number, since it uses as much as digits as its factorization.

31521131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90, while the sum is 17.

The square root of 31521131 is about 5614.3682636607. The cubic root of 31521131 is about 315.8885836715. Note that the first 3 decimals are identical.

Adding to 31521131 its reverse (13112513), we get a palindrome (44633644).

The spelling of 31521131 in words is "thirty-one million, five hundred twenty-one thousand, one hundred thirty-one".