20881540 has 24 divisors (see below), whose sum is σ = 44177112. Its totient is φ = 8290560.

The previous prime is 20881529. The next prime is 20881561. The reversal of 20881540 is 4518802.

It can be written as a sum of positive squares in 4 ways, for example, as 6380676 + 14500864 = 2526^2 + 3808^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20881499 and 20881508.

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, 1071 + ... + 6550.

It is an arithmetic number, because the mean of its divisors is an integer number (1840713).

Almost surely, 2^20881540 is an apocalyptic number.

20881540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20881540 is an abundant number, since it is smaller than the sum of its proper divisors (23295572).

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

20881540 is a wasteful number, since it uses less digits than its factorization.

20881540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7767 (or 7765 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 20881540 is about 4569.6323703335. The cubic root of 20881540 is about 275.3726737961.

The spelling of 20881540 in words is "twenty million, eight hundred eighty-one thousand, five hundred forty".