20528640 has 280 divisors, whose sum is σ = 80506008. Its totient is φ = 4976640.

The previous prime is 20528623. The next prime is 20528647. The reversal of 20528640 is 4682502.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20528647) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 1866235 + ... + 1866245.

Almost surely, 2^20528640 is an apocalyptic number.

20528640 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 20528640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40253004).

20528640 is an abundant number, since it is smaller than the sum of its proper divisors (59977368).

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

20528640 is an frugal number, since it uses more digits than its factorization.

20528640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 20528640 is about 4530.8542240951. The cubic root of 20528640 is about 273.8125771748.

The spelling of 20528640 in words is "twenty million, five hundred twenty-eight thousand, six hundred forty".