31921091 has 4 divisors (see below), whose sum is σ = 31938312. Its totient is φ = 31903872.

The previous prime is 31921081. The next prime is 31921111. The reversal of 31921091 is 19012913.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19012913 = 1511 ⋅12583.

It is a cyclic number.

It is not a de Polignac number, because 31921091 - 2⁶ = 31921027 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31921091.

It is not an unprimeable number, because it can be changed into a prime (31921081) 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, 5441 + ... + 9666.

It is an arithmetic number, because the mean of its divisors is an integer number (7984578).

Almost surely, 2^31921091 is an apocalyptic number.

31921091 is a deficient number, since it is larger than the sum of its proper divisors (17221).

31921091 is a wasteful number, since it uses less digits than its factorization.

31921091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17220.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 31921091 is about 5649.8753083586. The cubic root of 31921091 is about 317.2190367876.

The spelling of 31921091 in words is "thirty-one million, nine hundred twenty-one thousand, ninety-one".