21138569759 has 4 divisors (see below), whose sum is σ = 21146768760. Its totient is φ = 21130370760.

The previous prime is 21138569723. The next prime is 21138569779. The reversal of 21138569759 is 95796583112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21138569759 - 2⁸ = 21138569503 is a prime.

It is a super-2 number, since 2×21138569759² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138569779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4095632 + ... + 4100789.

It is an arithmetic number, because the mean of its divisors is an integer number (5286692190).

Almost surely, 2^21138569759 is an apocalyptic number.

21138569759 is a deficient number, since it is larger than the sum of its proper divisors (8199001).

21138569759 is an equidigital number, since it uses as much as digits as its factorization.

21138569759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8199000.

The product of its digits is 4082400, while the sum is 56.

The spelling of 21138569759 in words is "twenty-one billion, one hundred thirty-eight million, five hundred sixty-nine thousand, seven hundred fifty-nine".