20581540 has 24 divisors (see below), whose sum is σ = 49396032. Its totient is φ = 7056480.

The previous prime is 20581531. The next prime is 20581553. The reversal of 20581540 is 4518502.

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, 73366 + ... + 73645.

It is an arithmetic number, because the mean of its divisors is an integer number (2058168).

Almost surely, 2^20581540 is an apocalyptic number.

20581540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20581540 is an abundant number, since it is smaller than the sum of its proper divisors (28814492).

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

20581540 is a wasteful number, since it uses less digits than its factorization.

20581540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147027 (or 147025 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 20581540 is about 4536.6882193953. The cubic root of 20581540 is about 274.0475701945.

The spelling of 20581540 in words is "twenty million, five hundred eighty-one thousand, five hundred forty".