21665454 has 16 divisors (see below), whose sum is σ = 43648848. Its totient is φ = 7168832.

The previous prime is 21665401. The next prime is 21665473. The reversal of 21665454 is 45456612.

It is a super-2 number, since 2×21665454² = 938783794052232, which contains 22 as substring.

21665454 is a modest number, since divided by 5454 gives 2166 as remainder.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 12357 + ... + 14000.

It is an arithmetic number, because the mean of its divisors is an integer number (2728053).

Almost surely, 2^21665454 is an apocalyptic number.

21665454 is an abundant number, since it is smaller than the sum of its proper divisors (21983394).

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

21665454 is a wasteful number, since it uses less digits than its factorization.

21665454 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26499.

The product of its digits is 28800, while the sum is 33.

The square root of 21665454 is about 4654.6164181380. The cubic root of 21665454 is about 278.7763524189.

The spelling of 21665454 in words is "twenty-one million, six hundred sixty-five thousand, four hundred fifty-four".