20405900 has 18 divisors (see below), whose sum is σ = 44281020. Its totient is φ = 8162320.

The previous prime is 20405893. The next prime is 20405911. The reversal of 20405900 is 950402.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 101930 + ... + 102129.

Almost surely, 2^20405900 is an apocalyptic number.

20405900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20405900 is an abundant number, since it is smaller than the sum of its proper divisors (23875120).

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

20405900 is a wasteful number, since it uses less digits than its factorization.

20405900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204073 (or 204066 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 20405900 is about 4517.2890100147. The cubic root of 20405900 is about 273.2657807813.

The spelling of 20405900 in words is "twenty million, four hundred five thousand, nine hundred".