20557380 has 48 divisors (see below), whose sum is σ = 58302720. Its totient is φ = 5411328.

The previous prime is 20557351. The next prime is 20557387. The reversal of 20557380 is 8375502.

It is a happy number.

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

It is not an unprimeable number, because it can be changed into a prime (20557387) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2572 + ... + 6908.

It is an arithmetic number, because the mean of its divisors is an integer number (1214640).

Almost surely, 2^20557380 is an apocalyptic number.

20557380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20557380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29151360).

20557380 is an abundant number, since it is smaller than the sum of its proper divisors (37745340).

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

20557380 is a wasteful number, since it uses less digits than its factorization.

20557380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4428 (or 4426 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 20557380 is about 4534.0247021824. The cubic root of 20557380 is about 273.9402963671.

The spelling of 20557380 in words is "twenty million, five hundred fifty-seven thousand, three hundred eighty".