31121856 has 84 divisors (see below), whose sum is σ = 90580464. Its totient is φ = 10214400.

The previous prime is 31121833. The next prime is 31121869. The reversal of 31121856 is 65812113.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40516 + ... + 41276.

Almost surely, 2^31121856 is an apocalyptic number.

31121856 is a gapful number since it is divisible by the number (36) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31121856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45290232).

31121856 is an abundant number, since it is smaller than the sum of its proper divisors (59458608).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31121856 is a wasteful number, since it uses less digits than its factorization.

31121856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850 (or 837 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 31121856 is about 5578.6966219718. The cubic root of 31121856 is about 314.5491357804.

Adding to 31121856 its reverse (65812113), we get a palindrome (96933969).

The spelling of 31121856 in words is "thirty-one million, one hundred twenty-one thousand, eight hundred fifty-six".