21304078783 has 4 divisors (see below), whose sum is σ = 22942854088. Its totient is φ = 19665303480.

The previous prime is 21304078759. The next prime is 21304078793. The reversal of 21304078783 is 38787040312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21304078783 is a prime.

It is a super-2 number, since 2×21304078783² (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 (21304078793) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 819387633 + ... + 819387658.

It is an arithmetic number, because the mean of its divisors is an integer number (5735713522).

Almost surely, 2^21304078783 is an apocalyptic number.

21304078783 is a deficient number, since it is larger than the sum of its proper divisors (1638775305).

21304078783 is a wasteful number, since it uses less digits than its factorization.

21304078783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1638775304.

The product of its (nonzero) digits is 225792, while the sum is 43.

The spelling of 21304078783 in words is "twenty-one billion, three hundred four million, seventy-eight thousand, seven hundred eighty-three".