21015794 has 4 divisors (see below), whose sum is σ = 31523694. Its totient is φ = 10507896.

The previous prime is 21015773. The next prime is 21015803. The reversal of 21015794 is 49751012.

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., 19228225 + 1787569 = 4385^2 + 1337^2 .

It is an unprimeable number.

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, 5253947 + ... + 5253950.

Almost surely, 2^21015794 is an apocalyptic number.

21015794 is a deficient number, since it is larger than the sum of its proper divisors (10507900).

21015794 is a wasteful number, since it uses less digits than its factorization.

21015794 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10507899.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 21015794 is about 4584.2986377417. The cubic root of 21015794 is about 275.9615660968.

The spelling of 21015794 in words is "twenty-one million, fifteen thousand, seven hundred ninety-four".