31671601921 has 2 divisors, whose sum is σ = 31671601922. Its totient is φ = 31671601920.

The previous prime is 31671601909. The next prime is 31671601939. The reversal of 31671601921 is 12910617613.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29797664400 + 1873937521 = 172620^2 + 43289^2 .

It is a cyclic number.

It is not a de Polignac number, because 31671601921 - 2²³ = 31663213313 is a prime.

It is not a weakly prime, because it can be changed into another prime (31671605921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15835800960 + 15835800961.

It is an arithmetic number, because the mean of its divisors is an integer number (15835800961).

Almost surely, 2^31671601921 is an apocalyptic number.

It is an amenable number.

31671601921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31671601921 is an equidigital number, since it uses as much as digits as its factorization.

31671601921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 37.

The spelling of 31671601921 in words is "thirty-one billion, six hundred seventy-one million, six hundred one thousand, nine hundred twenty-one".