20731520 has 64 divisors (see below), whose sum is σ = 51316200. Its totient is φ = 7999488.

The previous prime is 20731499. The next prime is 20731553. The reversal of 20731520 is 2513702.

It can be written as a sum of positive squares in 4 ways, for example, as 11343424 + 9388096 = 3368^2 + 3064^2 .

It is a tau number, because it is divible by the number of its divisors (64).

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 = 20731492 and 20731501.

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, 18002 + ... + 19118.

Almost surely, 2^20731520 is an apocalyptic number.

20731520 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 20731520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25658100).

20731520 is an abundant number, since it is smaller than the sum of its proper divisors (30584680).

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

20731520 is a wasteful number, since it uses less digits than its factorization.

20731520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1165 (or 1153 counting only the distinct ones).

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

The square root of 20731520 is about 4553.1878942121. The cubic root of 20731520 is about 274.7116316033.

The spelling of 20731520 in words is "twenty million, seven hundred thirty-one thousand, five hundred twenty".