21801400 has 48 divisors (see below), whose sum is σ = 51548040. Its totient is φ = 8572800.

The previous prime is 21801383. The next prime is 21801407. The reversal of 21801400 is 410812.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21801407) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11307 + ... + 13093.

Almost surely, 2^21801400 is an apocalyptic number.

21801400 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 21801400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25774020).

21801400 is an abundant number, since it is smaller than the sum of its proper divisors (29746640).

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

21801400 is a wasteful number, since it uses less digits than its factorization.

21801400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1864 (or 1855 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 21801400 is about 4669.1969330925. The cubic root of 21801400 is about 279.3582240142.

It can be divided in two parts, 21801 and 400, that added together give a square (22201 = 149²).

The spelling of 21801400 in words is "twenty-one million, eight hundred one thousand, four hundred".