20643400 has 24 divisors (see below), whose sum is σ = 47996370. Its totient is φ = 8257280.

The previous prime is 20643379. The next prime is 20643407. The reversal of 20643400 is 434602.

It can be written as a sum of positive squares in 3 ways, for example, as 8988004 + 11655396 = 2998^2 + 3414^2 .

It is a super-2 number, since 2×20643400² = 852299927120000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20643407) 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, 51409 + ... + 51808.

Almost surely, 2^20643400 is an apocalyptic number.

20643400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20643400 is an abundant number, since it is smaller than the sum of its proper divisors (27352970).

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

20643400 is a wasteful number, since it uses less digits than its factorization.

20643400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103233 (or 103224 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 20643400 is about 4543.5008528667. The cubic root of 20643400 is about 274.3218552534.

The spelling of 20643400 in words is "twenty million, six hundred forty-three thousand, four hundred".