21157200 has 150 divisors (see below), whose sum is σ = 76047774. Its totient is φ = 5633280.

The previous prime is 21157139. The next prime is 21157207. The reversal of 21157200 is 275112.

It can be written as a sum of positive squares in 3 ways, for example, as 254016 + 20903184 = 504^2 + 4572^2 .

It is a tau number, because it is divible by the number of its divisors (150).

It is a super-2 number, since 2×21157200² = 895254223680000, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157207) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 32074 + ... + 32726.

Almost surely, 2^21157200 is an apocalyptic number.

21157200 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 21157200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38023887).

21157200 is an abundant number, since it is smaller than the sum of its proper divisors (54890574).

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

21157200 is a wasteful number, since it uses less digits than its factorization.

21157200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 683 (or 663 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21157200 is about 4599.6956421050. The cubic root of 21157200 is about 276.5791242521.

The spelling of 21157200 in words is "twenty-one million, one hundred fifty-seven thousand, two hundred".