21947400 has 144 divisors (see below), whose sum is σ = 75078900. Its totient is φ = 5744640.

The previous prime is 21947389. The next prime is 21947407. The reversal of 21947400 is 474912.

It is a happy number.

21947400 is a `hidden beast` number, since 219 + 47 + 400 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 5447556 + 16499844 = 2334^2 + 4062^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21947407) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 160132 + ... + 160268.

Almost surely, 2^21947400 is an apocalyptic number.

21947400 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 21947400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37539450).

21947400 is an abundant number, since it is smaller than the sum of its proper divisors (53131500).

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

21947400 is a wasteful number, since it uses less digits than its factorization.

21947400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248 (or 236 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21947400 is about 4684.8052254069. The cubic root of 21947400 is about 279.9804408106.

The spelling of 21947400 in words is "twenty-one million, nine hundred forty-seven thousand, four hundred".