20731540 has 24 divisors (see below), whose sum is σ = 43637832. Its totient is φ = 8273280.

The previous prime is 20731499. The next prime is 20731553. The reversal of 20731540 is 4513702.

It can be written as a sum of positive squares in 4 ways, for example, as 1774224 + 18957316 = 1332^2 + 4354^2 .

It is a congruent number.

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, 10210 + ... + 12070.

It is an arithmetic number, because the mean of its divisors is an integer number (1818243).

Almost surely, 2^20731540 is an apocalyptic number.

20731540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20731540 is an abundant number, since it is smaller than the sum of its proper divisors (22906292).

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

20731540 is a wasteful number, since it uses less digits than its factorization.

20731540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2427 (or 2425 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 20731540 is about 4553.1900904750. The cubic root of 20731540 is about 274.7117199427.

The spelling of 20731540 in words is "twenty million, seven hundred thirty-one thousand, five hundred forty".