21660672 has 88 divisors (see below), whose sum is σ = 63080352. Its totient is φ = 6553600.

The previous prime is 21660643. The next prime is 21660677. The reversal of 21660672 is 27606612.

It is a tau number, because it is divible by the number of its divisors (88).

It is a super-2 number, since 2×21660672² = 938369422983168, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21660677) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33472 + ... + 34112.

Almost surely, 2^21660672 is an apocalyptic number.

21660672 is a gapful number since it is divisible by the number (22) 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 21660672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31540176).

21660672 is an abundant number, since it is smaller than the sum of its proper divisors (41419680).

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

21660672 is a wasteful number, since it uses less digits than its factorization.

21660672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 675 (or 657 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 21660672 is about 4654.1027062152. The cubic root of 21660672 is about 278.7558403999.

The spelling of 21660672 in words is "twenty-one million, six hundred sixty thousand, six hundred seventy-two".