20557540 has 24 divisors (see below), whose sum is σ = 43602552. Its totient is φ = 8140800.

The previous prime is 20557507. The next prime is 20557571. The reversal of 20557540 is 4575502.

It can be written as a sum of positive squares in 4 ways, for example, as 8433216 + 12124324 = 2904^2 + 3482^2 .

It is a super-2 number, since 2×20557540² = 845224901703200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20557499 and 20557508.

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, 3069 + ... + 7108.

It is an arithmetic number, because the mean of its divisors is an integer number (1816773).

Almost surely, 2^20557540 is an apocalyptic number.

20557540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20557540 is an abundant number, since it is smaller than the sum of its proper divisors (23045012).

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

20557540 is a wasteful number, since it uses less digits than its factorization.

20557540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10287 (or 10285 counting only the distinct ones).

The product of its (nonzero) digits is 7000, while the sum is 28.

The square root of 20557540 is about 4534.0423465160. The cubic root of 20557540 is about 273.9410070662.

The spelling of 20557540 in words is "twenty million, five hundred fifty-seven thousand, five hundred forty".