31431340021 has 2 divisors, whose sum is σ = 31431340022. Its totient is φ = 31431340020.

The previous prime is 31431340013. The next prime is 31431340027. The reversal of 31431340021 is 12004313413.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31288656996 + 142683025 = 176886^2 + 11945^2 .

It is a cyclic number.

It is not a de Polignac number, because 31431340021 - 2³ = 31431340013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31431339974 and 31431340001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31431340027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15715670010 + 15715670011.

It is an arithmetic number, because the mean of its divisors is an integer number (15715670011).

Almost surely, 2^31431340021 is an apocalyptic number.

It is an amenable number.

31431340021 is a deficient number, since it is larger than the sum of its proper divisors (1).

31431340021 is an equidigital number, since it uses as much as digits as its factorization.

31431340021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 22.

Adding to 31431340021 its reverse (12004313413), we get a palindrome (43435653434).

The spelling of 31431340021 in words is "thirty-one billion, four hundred thirty-one million, three hundred forty thousand, twenty-one".