21064643774 has 4 divisors (see below), whose sum is σ = 31596965664. Its totient is φ = 10532321886.

The previous prime is 21064643773. The next prime is 21064643779. The reversal of 21064643774 is 47734646012.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21064643773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5266160942 + ... + 5266160945.

It is an arithmetic number, because the mean of its divisors is an integer number (7899241416).

Almost surely, 2^21064643774 is an apocalyptic number.

21064643774 is a deficient number, since it is larger than the sum of its proper divisors (10532321890).

21064643774 is a wasteful number, since it uses less digits than its factorization.

21064643774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10532321889.

The product of its (nonzero) digits is 677376, while the sum is 44.

The spelling of 21064643774 in words is "twenty-one billion, sixty-four million, six hundred forty-three thousand, seven hundred seventy-four".