21998821307 has 4 divisors (see below), whose sum is σ = 22708460736. Its totient is φ = 21289181880.

The previous prime is 21998821291. The next prime is 21998821309. The reversal of 21998821307 is 70312889912.

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 21998821307 - 2⁴ = 21998821291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21998821309) 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, 354819668 + ... + 354819729.

It is an arithmetic number, because the mean of its divisors is an integer number (5677115184).

Almost surely, 2^21998821307 is an apocalyptic number.

21998821307 is a deficient number, since it is larger than the sum of its proper divisors (709639429).

21998821307 is an equidigital number, since it uses as much as digits as its factorization.

21998821307 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709639428.

The product of its (nonzero) digits is 435456, while the sum is 50.

The spelling of 21998821307 in words is "twenty-one billion, nine hundred ninety-eight million, eight hundred twenty-one thousand, three hundred seven".