31161621 has 4 divisors (see below), whose sum is σ = 41548832. Its totient is φ = 20774412.

The previous prime is 31161607. The next prime is 31161643. The reversal of 31161621 is 12616113.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12616113 = 3 ⋅4205371.

It is not a de Polignac number, because 31161621 - 2⁵ = 31161589 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31161601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5193601 + ... + 5193606.

It is an arithmetic number, because the mean of its divisors is an integer number (10387208).

Almost surely, 2^31161621 is an apocalyptic number.

It is an amenable number.

31161621 is a deficient number, since it is larger than the sum of its proper divisors (10387211).

31161621 is a wasteful number, since it uses less digits than its factorization.

31161621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10387210.

The product of its digits is 216, while the sum is 21.

The square root of 31161621 is about 5582.2594887733. The cubic root of 31161621 is about 314.6830472766.

Adding to 31161621 its reverse (12616113), we get a palindrome (43777734).

The spelling of 31161621 in words is "thirty-one million, one hundred sixty-one thousand, six hundred twenty-one".