20531720 has 32 divisors (see below), whose sum is σ = 50397120. Its totient is φ = 7465920.

The previous prime is 20531717. The next prime is 20531741. The reversal of 20531720 is 2713502.

It is a super-3 number, since 3×20531720³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 20531692 and 20531701.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22892 + ... + 23771.

It is an arithmetic number, because the mean of its divisors is an integer number (1574910).

Almost surely, 2^20531720 is an apocalyptic number.

20531720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20531720 is an abundant number, since it is smaller than the sum of its proper divisors (29865400).

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

20531720 is a wasteful number, since it uses less digits than its factorization.

20531720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46685 (or 46681 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 20.

The square root of 20531720 is about 4531.1941031035. The cubic root of 20531720 is about 273.8262702489.

It can be divided in two parts, 2053 and 1720, that added together give a palindrome (3773).

The spelling of 20531720 in words is "twenty million, five hundred thirty-one thousand, seven hundred twenty".