21265604 has 6 divisors (see below), whose sum is σ = 37214814. Its totient is φ = 10632800.

The previous prime is 21265603. The next prime is 21265619. The reversal of 21265604 is 40656212.

It can be written as a sum of positive squares in only one way, i.e., 19009600 + 2256004 = 4360^2 + 1502^2 .

It is not an unprimeable number, because it can be changed into a prime (21265603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2658197 + ... + 2658204.

It is an arithmetic number, because the mean of its divisors is an integer number (6202469).

Almost surely, 2^21265604 is an apocalyptic number.

It is an amenable number.

21265604 is a deficient number, since it is larger than the sum of its proper divisors (15949210).

21265604 is a wasteful number, since it uses less digits than its factorization.

21265604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5316405 (or 5316403 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21265604 is about 4611.4644094908. The cubic root of 21265604 is about 277.0506929774.

The spelling of 21265604 in words is "twenty-one million, two hundred sixty-five thousand, six hundred four".