21747791764 has 12 divisors (see below), whose sum is σ = 38078176500. Its totient is φ = 10868312768.

The previous prime is 21747791753. The next prime is 21747791803. The reversal of 21747791764 is 46719774712.

It can be written as a sum of positive squares in 2 ways, for example, as 9082090000 + 12665701764 = 95300^2 + 112542^2 .

It is a super-2 number, since 2×21747791764² (a number of 21 digits) contains 22 as substring.

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, 1387009 + ... + 1402600.

It is an arithmetic number, because the mean of its divisors is an integer number (3173181375).

Almost surely, 2^21747791764 is an apocalyptic number.

It is an amenable number.

21747791764 is a deficient number, since it is larger than the sum of its proper divisors (16330384736).

21747791764 is a wasteful number, since it uses less digits than its factorization.

21747791764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2791562 (or 2791560 counting only the distinct ones).

The product of its digits is 4148928, while the sum is 55.

The spelling of 21747791764 in words is "twenty-one billion, seven hundred forty-seven million, seven hundred ninety-one thousand, seven hundred sixty-four".