31121880 has 64 divisors (see below), whose sum is σ = 93864960. Its totient is φ = 8254848.

The previous prime is 31121869. The next prime is 31121887. The reversal of 31121880 is 8812113.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 31121880.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121887) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26179 + ... + 27341.

It is an arithmetic number, because the mean of its divisors is an integer number (1466640).

Almost surely, 2^31121880 is an apocalyptic number.

31121880 is a gapful number since it is divisible by the number (30) 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 31121880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46932480).

31121880 is an abundant number, since it is smaller than the sum of its proper divisors (62743080).

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

31121880 is a wasteful number, since it uses less digits than its factorization.

31121880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1400 (or 1396 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 31121880 is about 5578.6987730115. The cubic root of 31121880 is about 314.5492166365.

Adding to 31121880 its reverse (8812113), we get a palindrome (39933993).

The spelling of 31121880 in words is "thirty-one million, one hundred twenty-one thousand, eight hundred eighty".