31409921 has 2 divisors, whose sum is σ = 31409922. Its totient is φ = 31409920.

The previous prime is 31409857. The next prime is 31409923. The reversal of 31409921 is 12990413.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23902321 + 7507600 = 4889^2 + 2740^2 .

It is a cyclic number.

It is not a de Polignac number, because 31409921 - 2⁶ = 31409857 is a prime.

Together with 31409923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31409923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15704960 + 15704961.

It is an arithmetic number, because the mean of its divisors is an integer number (15704961).

Almost surely, 2^31409921 is an apocalyptic number.

It is an amenable number.

31409921 is a deficient number, since it is larger than the sum of its proper divisors (1).

31409921 is an equidigital number, since it uses as much as digits as its factorization.

31409921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 29.

The square root of 31409921 is about 5604.4554597213. The cubic root of 31409921 is about 315.5166494211.

The spelling of 31409921 in words is "thirty-one million, four hundred nine thousand, nine hundred twenty-one".