31684621 has 4 divisors (see below), whose sum is σ = 31696092. Its totient is φ = 31673152.

The previous prime is 31684607. The next prime is 31684637. The reversal of 31684621 is 12648613.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5827396 + 25857225 = 2414^2 + 5085^2 .

It is a cyclic number.

It is not a de Polignac number, because 31684621 - 2⁵ = 31684589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31684661) 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 in 3 ways as a sum of consecutive naturals, for example, 1221 + ... + 8053.

It is an arithmetic number, because the mean of its divisors is an integer number (7924023).

Almost surely, 2^31684621 is an apocalyptic number.

It is an amenable number.

31684621 is a deficient number, since it is larger than the sum of its proper divisors (11471).

31684621 is an equidigital number, since it uses as much as digits as its factorization.

31684621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11470.

The product of its digits is 6912, while the sum is 31.

The square root of 31684621 is about 5628.9093970324. The cubic root of 31684621 is about 316.4337797697.

The spelling of 31684621 in words is "thirty-one million, six hundred eighty-four thousand, six hundred twenty-one".