20931288 has 64 divisors (see below), whose sum is σ = 62415360. Its totient is φ = 5719296.

The previous prime is 20931263. The next prime is 20931289. The reversal of 20931288 is 88213902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931289) 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, 1156 + ... + 6572.

It is an arithmetic number, because the mean of its divisors is an integer number (975240).

Almost surely, 2^20931288 is an apocalyptic number.

20931288 is a gapful number since it is divisible by the number (28) 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 20931288, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31207680).

20931288 is an abundant number, since it is smaller than the sum of its proper divisors (41484072).

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

20931288 is a wasteful number, since it uses less digits than its factorization.

20931288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5456 (or 5452 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 20931288 is about 4575.0724584426. The cubic root of 20931288 is about 275.5911821879.

The spelling of 20931288 in words is "twenty million, nine hundred thirty-one thousand, two hundred eighty-eight".