21157746 has 32 divisors (see below), whose sum is σ = 44513280. Its totient is φ = 6691344.

The previous prime is 21157739. The next prime is 21157751. The reversal of 21157746 is 64775112.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 18631 + ... + 19733.

It is an arithmetic number, because the mean of its divisors is an integer number (1391040).

Almost surely, 2^21157746 is an apocalyptic number.

21157746 is an abundant number, since it is smaller than the sum of its proper divisors (23355534).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21157746 is a wasteful number, since it uses less digits than its factorization.

21157746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1270.

The product of its digits is 11760, while the sum is 33.

The square root of 21157746 is about 4599.7549934752. The cubic root of 21157746 is about 276.5815034406.

The spelling of 21157746 in words is "twenty-one million, one hundred fifty-seven thousand, seven hundred forty-six".