21165874 has 4 divisors (see below), whose sum is σ = 31748814. Its totient is φ = 10582936.

The previous prime is 21165871. The next prime is 21165883. The reversal of 21165874 is 47856112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 21095649 + 70225 = 4593^2 + 265^2 .

It is not an unprimeable number, because it can be changed into a prime (21165871) by changing a digit.

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 as a sum of consecutive naturals, namely, 5291467 + ... + 5291470.

Almost surely, 2^21165874 is an apocalyptic number.

21165874 is a deficient number, since it is larger than the sum of its proper divisors (10582940).

21165874 is a wasteful number, since it uses less digits than its factorization.

21165874 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10582939.

The product of its digits is 13440, while the sum is 34.

The square root of 21165874 is about 4600.6384339567. The cubic root of 21165874 is about 276.6169162653.

The spelling of 21165874 in words is "twenty-one million, one hundred sixty-five thousand, eight hundred seventy-four".