31221241391 has 4 divisors (see below), whose sum is σ = 31239640992. Its totient is φ = 31202841792.

The previous prime is 31221241367. The next prime is 31221241433. The reversal of 31221241391 is 19314212213.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31221241391 is a prime.

It is a super-2 number, since 2×31221241391² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31221241991) 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, 9197255 + ... + 9200648.

It is an arithmetic number, because the mean of its divisors is an integer number (7809910248).

Almost surely, 2^31221241391 is an apocalyptic number.

31221241391 is a deficient number, since it is larger than the sum of its proper divisors (18399601).

31221241391 is a wasteful number, since it uses less digits than its factorization.

31221241391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18399600.

The product of its digits is 2592, while the sum is 29.

The spelling of 31221241391 in words is "thirty-one billion, two hundred twenty-one million, two hundred forty-one thousand, three hundred ninety-one".