20731560 has 64 divisors (see below), whose sum is σ = 64212480. Its totient is φ = 5349120.

The previous prime is 20731553. The next prime is 20731567. The reversal of 20731560 is 6513702.

It is an interprime number because it is at equal distance from previous prime (20731553) and next prime (20731567).

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 20731560.

It is not an unprimeable number, because it can be changed into a prime (20731567) 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, 934 + ... + 6506.

It is an arithmetic number, because the mean of its divisors is an integer number (1003320).

Almost surely, 2^20731560 is an apocalyptic number.

20731560 is a gapful number since it is divisible by the number (20) 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 20731560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32106240).

20731560 is an abundant number, since it is smaller than the sum of its proper divisors (43480920).

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

20731560 is a wasteful number, since it uses less digits than its factorization.

20731560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5618 (or 5614 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 20731560 is about 4553.1922867369. The cubic root of 20731560 is about 274.7118082821.

The spelling of 20731560 in words is "twenty million, seven hundred thirty-one thousand, five hundred sixty".