20865540 has 24 divisors (see below), whose sum is σ = 58423680. Its totient is φ = 5564128.

The previous prime is 20865497. The next prime is 20865541. The reversal of 20865540 is 4556802.

20865540 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20865498 and 20865507.

It is not an unprimeable number, because it can be changed into a prime (20865541) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173820 + ... + 173939.

It is an arithmetic number, because the mean of its divisors is an integer number (2434320).

Almost surely, 2^20865540 is an apocalyptic number.

20865540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20865540 is an abundant number, since it is smaller than the sum of its proper divisors (37558140).

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

20865540 is a wasteful number, since it uses less digits than its factorization.

20865540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347771 (or 347769 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 30.

The square root of 20865540 is about 4567.8813469704. The cubic root of 20865540 is about 275.3023231645.

It can be divided in two parts, 2086 and 5540, that added together give a triangular number (7626 = T₁₂₃).

The spelling of 20865540 in words is "twenty million, eight hundred sixty-five thousand, five hundred forty".