21791078 has 8 divisors (see below), whose sum is σ = 33741120. Its totient is φ = 10544040.

The previous prime is 21791057. The next prime is 21791087. The reversal of 21791078 is 87019712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175673 + ... + 175796.

It is an arithmetic number, because the mean of its divisors is an integer number (4217640).

Almost surely, 2^21791078 is an apocalyptic number.

21791078 is a deficient number, since it is larger than the sum of its proper divisors (11950042).

21791078 is a wasteful number, since it uses less digits than its factorization.

21791078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351502.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21791078 is about 4668.0914729684. The cubic root of 21791078 is about 279.3141291276.

The spelling of 21791078 in words is "twenty-one million, seven hundred ninety-one thousand, seventy-eight".