31854721 has 2 divisors, whose sum is σ = 31854722. Its totient is φ = 31854720.

The previous prime is 31854689. The next prime is 31854751. The reversal of 31854721 is 12745813.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23902321 + 7952400 = 4889^2 + 2820^2 .

It is an emirp because it is prime and its reverse (12745813) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31854721 - 2⁵ = 31854689 is a prime.

It is not a weakly prime, because it can be changed into another prime (31854751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15927360 + 15927361.

It is an arithmetic number, because the mean of its divisors is an integer number (15927361).

Almost surely, 2^31854721 is an apocalyptic number.

It is an amenable number.

31854721 is a deficient number, since it is larger than the sum of its proper divisors (1).

31854721 is an equidigital number, since it uses as much as digits as its factorization.

31854721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 31.

The square root of 31854721 is about 5643.9986711551. The cubic root of 31854721 is about 316.9990314001. Note that the first 3 decimals are identical.

The spelling of 31854721 in words is "thirty-one million, eight hundred fifty-four thousand, seven hundred twenty-one".