21249729765 has 24 divisors (see below), whose sum is σ = 40181308128. Its totient is φ = 10302899040.

The previous prime is 21249729733. The next prime is 21249729779. The reversal of 21249729765 is 56792794212.

21249729765 is a `hidden beast` number, since 2 + 1 + 2 + 497 + 2 + 97 + 65 = 666.

It is not a de Polignac number, because 21249729765 - 2⁵ = 21249729733 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21463879 + ... + 21464868.

It is an arithmetic number, because the mean of its divisors is an integer number (1674221172).

Almost surely, 2^21249729765 is an apocalyptic number.

It is an amenable number.

21249729765 is a deficient number, since it is larger than the sum of its proper divisors (18931578363).

21249729765 is a wasteful number, since it uses less digits than its factorization.

21249729765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42928769 (or 42928766 counting only the distinct ones).

The product of its digits is 3810240, while the sum is 54.

The spelling of 21249729765 in words is "twenty-one billion, two hundred forty-nine million, seven hundred twenty-nine thousand, seven hundred sixty-five".