21166004 has 12 divisors (see below), whose sum is σ = 37944228. Its totient is φ = 10324800.

The previous prime is 21165997. The next prime is 21166007. The reversal of 21166004 is 40066112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8133904 + 13032100 = 2852^2 + 3610^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21166007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64367 + ... + 64694.

It is an arithmetic number, because the mean of its divisors is an integer number (3162019).

Almost surely, 2^21166004 is an apocalyptic number.

It is an amenable number.

21166004 is a deficient number, since it is larger than the sum of its proper divisors (16778224).

21166004 is a wasteful number, since it uses less digits than its factorization.

21166004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129106 (or 129104 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21166004 is about 4600.6525624089. The cubic root of 21166004 is about 276.6174825877.

The spelling of 21166004 in words is "twenty-one million, one hundred sixty-six thousand, four".