21665466 has 48 divisors (see below), whose sum is σ = 49690368. Its totient is φ = 6811200.

The previous prime is 21665401. The next prime is 21665473. The reversal of 21665466 is 66456612.

It is a happy number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21665466.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22405 + ... + 23351.

It is an arithmetic number, because the mean of its divisors is an integer number (1035216).

Almost surely, 2^21665466 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21665466, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24845184).

21665466 is an abundant number, since it is smaller than the sum of its proper divisors (28024902).

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

21665466 is a wasteful number, since it uses less digits than its factorization.

21665466 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1027 (or 1024 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 21665466 is about 4654.6177071807. The cubic root of 21665466 is about 278.7764038882.

The spelling of 21665466 in words is "twenty-one million, six hundred sixty-five thousand, four hundred sixty-six".