31221091 has 4 divisors (see below), whose sum is σ = 34059384. Its totient is φ = 28382800.

The previous prime is 31221041. The next prime is 31221103. The reversal of 31221091 is 19012213.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31221091 - 2⁷ = 31220963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31221041) 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, 1419130 + ... + 1419151.

It is an arithmetic number, because the mean of its divisors is an integer number (8514846).

Almost surely, 2^31221091 is an apocalyptic number.

31221091 is a deficient number, since it is larger than the sum of its proper divisors (2838293).

31221091 is a wasteful number, since it uses less digits than its factorization.

31221091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2838292.

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

The square root of 31221091 is about 5587.5836459063. The cubic root of 31221091 is about 314.8831043539.

It can be divided in two parts, 31 and 221091, that added together give a palindrome (221122).

The spelling of 31221091 in words is "thirty-one million, two hundred twenty-one thousand, ninety-one".