20531988 has 96 divisors (see below), whose sum is σ = 57697920. Its totient is φ = 6289920.

The previous prime is 20531983. The next prime is 20531999. The reversal of 20531988 is 88913502.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20531981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 97203 + ... + 97413.

It is an arithmetic number, because the mean of its divisors is an integer number (601020).

Almost surely, 2^20531988 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20531988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28848960).

20531988 is an abundant number, since it is smaller than the sum of its proper divisors (37165932).

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

20531988 is a wasteful number, since it uses less digits than its factorization.

20531988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294 (or 286 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 20531988 is about 4531.2236757856. The cubic root of 20531988 is about 273.8274616594.

The spelling of 20531988 in words is "twenty million, five hundred thirty-one thousand, nine hundred eighty-eight".