21781912337 has 8 divisors (see below), whose sum is σ = 23068675656. Its totient is φ = 20495757312.

The previous prime is 21781912333. The next prime is 21781912381. The reversal of 21781912337 is 73321918712.

It can be written as a sum of positive squares in 4 ways, for example, as 5371277521 + 16410634816 = 73289^2 + 128104^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21781912337 - 2² = 21781912333 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21781912333) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 77288 + ... + 222569.

It is an arithmetic number, because the mean of its divisors is an integer number (2883584457).

Almost surely, 2^21781912337 is an apocalyptic number.

It is an amenable number.

21781912337 is a deficient number, since it is larger than the sum of its proper divisors (1286763319).

21781912337 is a wasteful number, since it uses less digits than its factorization.

21781912337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304147.

The product of its digits is 127008, while the sum is 44.

The spelling of 21781912337 in words is "twenty-one billion, seven hundred eighty-one million, nine hundred twelve thousand, three hundred thirty-seven".