21918660783 has 4 divisors (see below), whose sum is σ = 29224881048. Its totient is φ = 14612440520.

The previous prime is 21918660739. The next prime is 21918660793. The reversal of 21918660783 is 38706681912.

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 21918660783 - 2⁹ = 21918660271 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21918660793) 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, 3653110128 + ... + 3653110133.

It is an arithmetic number, because the mean of its divisors is an integer number (7306220262).

Almost surely, 2^21918660783 is an apocalyptic number.

21918660783 is a deficient number, since it is larger than the sum of its proper divisors (7306220265).

21918660783 is an equidigital number, since it uses as much as digits as its factorization.

21918660783 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7306220264.

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 21918660783 in words is "twenty-one billion, nine hundred eighteen million, six hundred sixty thousand, seven hundred eighty-three".