31212091 has 4 divisors (see below), whose sum is σ = 32288400. Its totient is φ = 30135784.

The previous prime is 31212061. The next prime is 31212113. The reversal of 31212091 is 19021213.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19021213 = 977 ⋅19469.

It is a cyclic number.

It is not a de Polignac number, because 31212091 - 2⁵ = 31212059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31212001) 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, 538111 + ... + 538168.

It is an arithmetic number, because the mean of its divisors is an integer number (8072100).

Almost surely, 2^31212091 is an apocalyptic number.

31212091 is a deficient number, since it is larger than the sum of its proper divisors (1076309).

31212091 is a wasteful number, since it uses less digits than its factorization.

31212091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1076308.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 31212091 is about 5586.7782307874. The cubic root of 31212091 is about 314.8528446779.

It can be divided in two parts, 312 and 12091, that added together give a triangular number (12403 = T₁₅₇).

The spelling of 31212091 in words is "thirty-one million, two hundred twelve thousand, ninety-one".