21665104 has 10 divisors (see below), whose sum is σ = 41976170. Its totient is φ = 10832544.

The previous prime is 21665101. The next prime is 21665129. The reversal of 21665104 is 40156612.

It can be written as a sum of positive squares in only one way, i.e., 14047504 + 7617600 = 3748^2 + 2760^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 677019 + ... + 677050.

It is an arithmetic number, because the mean of its divisors is an integer number (4197617).

Almost surely, 2^21665104 is an apocalyptic number.

It is an amenable number.

21665104 is a deficient number, since it is larger than the sum of its proper divisors (20311066).

21665104 is a wasteful number, since it uses less digits than its factorization.

21665104 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1354077 (or 1354071 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21665104 is about 4654.5788209031. The cubic root of 21665104 is about 278.7748512234.

The spelling of 21665104 in words is "twenty-one million, six hundred sixty-five thousand, one hundred four".