21725660 has 96 divisors (see below), whose sum is σ = 54468288. Its totient is φ = 7188480.

The previous prime is 21725659. The next prime is 21725663. The reversal of 21725660 is 6652712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 138302 + ... + 138458.

It is an arithmetic number, because the mean of its divisors is an integer number (567378).

Almost surely, 2^21725660 is an apocalyptic number.

21725660 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 21725660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27234144).

21725660 is an abundant number, since it is smaller than the sum of its proper divisors (32742628).

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

21725660 is a wasteful number, since it uses less digits than its factorization.

21725660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231 (or 229 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 21725660 is about 4661.0792741596. The cubic root of 21725660 is about 279.0343435667.

The spelling of 21725660 in words is "twenty-one million, seven hundred twenty-five thousand, six hundred sixty".