21265759757 has 4 divisors (see below), whose sum is σ = 23199010656. Its totient is φ = 19332508860.

The previous prime is 21265759661. The next prime is 21265759787. The reversal of 21265759757 is 75795756212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21265759757 - 2¹⁰ = 21265758733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21265759787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 966625433 + ... + 966625454.

It is an arithmetic number, because the mean of its divisors is an integer number (5799752664).

Almost surely, 2^21265759757 is an apocalyptic number.

It is an amenable number.

21265759757 is a deficient number, since it is larger than the sum of its proper divisors (1933250899).

21265759757 is a wasteful number, since it uses less digits than its factorization.

21265759757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1933250898.

The product of its digits is 9261000, while the sum is 56.

The spelling of 21265759757 in words is "twenty-one billion, two hundred sixty-five million, seven hundred fifty-nine thousand, seven hundred fifty-seven".