21650400 has 216 divisors, whose sum is σ = 79619904. Its totient is φ = 5529600.

The previous prime is 21650399. The next prime is 21650411. The reversal of 21650400 is 405612.

It is a happy number.

21650400 is a `hidden beast` number, since 216 + 50 + 400 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 223152 + ... + 223248.

Almost surely, 2^21650400 is an apocalyptic number.

21650400 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 21650400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39809952).

21650400 is an abundant number, since it is smaller than the sum of its proper divisors (57969504).

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

21650400 is a wasteful number, since it uses less digits than its factorization.

21650400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21650400 is about 4652.9990328819. Note that the first 3 decimals coincide. The cubic root of 21650400 is about 278.7117692412.

The spelling of 21650400 in words is "twenty-one million, six hundred fifty thousand, four hundred".