21739253761 has 4 divisors (see below), whose sum is σ = 23018033412. Its totient is φ = 20460474112.

The previous prime is 21739253707. The next prime is 21739253771. The reversal of 21739253761 is 16735293712.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5893479361 + 15845774400 = 76769^2 + 125880^2 .

It is a cyclic number.

It is not a de Polignac number, because 21739253761 - 2¹³ = 21739245569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21739253771) by changing a digit.

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, 639389800 + ... + 639389833.

It is an arithmetic number, because the mean of its divisors is an integer number (5754508353).

Almost surely, 2^21739253761 is an apocalyptic number.

It is an amenable number.

21739253761 is a deficient number, since it is larger than the sum of its proper divisors (1278779651).

21739253761 is a wasteful number, since it uses less digits than its factorization.

21739253761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1278779650.

The product of its digits is 476280, while the sum is 46.

The spelling of 21739253761 in words is "twenty-one billion, seven hundred thirty-nine million, two hundred fifty-three thousand, seven hundred sixty-one".