20928400 has 30 divisors (see below), whose sum is σ = 50281442. Its totient is φ = 8371200.

The previous prime is 20928373. The next prime is 20928407. The reversal of 20928400 is 482902.

It can be written as a sum of positive squares in 3 ways, for example, as 389376 + 20539024 = 624^2 + 4532^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20928407) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 25761 + ... + 26560.

Almost surely, 2^20928400 is an apocalyptic number.

20928400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20928400 is an abundant number, since it is smaller than the sum of its proper divisors (29353042).

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

20928400 is a wasteful number, since it uses less digits than its factorization.

20928400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52339 (or 52328 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 20928400 is about 4574.7568241383. The cubic root of 20928400 is about 275.5785066828.

The spelling of 20928400 in words is "twenty million, nine hundred twenty-eight thousand, four hundred".