21009779999 has 8 divisors (see below), whose sum is σ = 22634062752. Its totient is φ = 19386660960.

The previous prime is 21009779983. The next prime is 21009780007. The reversal of 21009779999 is 99997790012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21009779999 - 2⁴ = 21009779983 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 (21009779599) 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 7 ways as a sum of consecutive naturals, for example, 253244 + ... + 325809.

It is an arithmetic number, because the mean of its divisors is an integer number (2829257844).

Almost surely, 2^21009779999 is an apocalyptic number.

21009779999 is a deficient number, since it is larger than the sum of its proper divisors (1624282753).

21009779999 is a wasteful number, since it uses less digits than its factorization.

21009779999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581857.

The product of its (nonzero) digits is 5786802, while the sum is 62.

The spelling of 21009779999 in words is "twenty-one billion, nine million, seven hundred seventy-nine thousand, nine hundred ninety-nine".