21728466 has 16 divisors (see below), whose sum is σ = 48285600. Its totient is φ = 7242804.

The previous prime is 21728437. The next prime is 21728467. The reversal of 21728466 is 66482712.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21728466.

It is not an unprimeable number, because it can be changed into a prime (21728467) 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, 201136 + ... + 201243.

It is an arithmetic number, because the mean of its divisors is an integer number (3017850).

Almost surely, 2^21728466 is an apocalyptic number.

21728466 is an abundant number, since it is smaller than the sum of its proper divisors (26557134).

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

21728466 is a wasteful number, since it uses less digits than its factorization.

21728466 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 402390 (or 402384 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21728466 is about 4661.3802676890. The cubic root of 21728466 is about 279.0463560390.

The spelling of 21728466 in words is "twenty-one million, seven hundred twenty-eight thousand, four hundred sixty-six".