20557530 has 128 divisors (see below), whose sum is σ = 63936000. Its totient is φ = 4603392.

The previous prime is 20557507. The next prime is 20557571. The reversal of 20557530 is 3575502.

It is a super-2 number, since 2×20557530² = 845224079401800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 20557494 and 20557503.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 137896 + ... + 138044.

It is an arithmetic number, because the mean of its divisors is an integer number (499500).

Almost surely, 2^20557530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20557530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31968000).

20557530 is an abundant number, since it is smaller than the sum of its proper divisors (43378470).

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

20557530 is a wasteful number, since it uses less digits than its factorization.

20557530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 5250, while the sum is 27.

The square root of 20557530 is about 4534.0412437471. The cubic root of 20557530 is about 273.9409626476.

The spelling of 20557530 in words is "twenty million, five hundred fifty-seven thousand, five hundred thirty".