21072874 has 4 divisors (see below), whose sum is σ = 31609314. Its totient is φ = 10536436.

The previous prime is 21072847. The next prime is 21072889. The reversal of 21072874 is 47827012.

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., 19421649 + 1651225 = 4407^2 + 1285^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5268217 + ... + 5268220.

Almost surely, 2^21072874 is an apocalyptic number.

21072874 is a deficient number, since it is larger than the sum of its proper divisors (10536440).

21072874 is a wasteful number, since it uses less digits than its factorization.

21072874 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10536439.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 21072874 is about 4590.5200141160. The cubic root of 21072874 is about 276.2111822773.

Adding to 21072874 its reverse (47827012), we get a palindrome (68899886).

The spelling of 21072874 in words is "twenty-one million, seventy-two thousand, eight hundred seventy-four".