21257794066 has 8 divisors (see below), whose sum is σ = 31898809404. Its totient is φ = 10624857600.

The previous prime is 21257794039. The next prime is 21257794087. The reversal of 21257794066 is 66049775212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21234609841 + 23184225 = 145721^2 + 4815^2 .

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

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 3 ways as a sum of consecutive naturals, for example, 2013135 + ... + 2023666.

Almost surely, 2^21257794066 is an apocalyptic number.

21257794066 is a deficient number, since it is larger than the sum of its proper divisors (10641015338).

21257794066 is a wasteful number, since it uses less digits than its factorization.

21257794066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4039436.

The product of its (nonzero) digits is 1270080, while the sum is 49.

The spelling of 21257794066 in words is "twenty-one billion, two hundred fifty-seven million, seven hundred ninety-four thousand, sixty-six".