21996407309 has 4 divisors (see below), whose sum is σ = 22411433916. Its totient is φ = 21581380704.

The previous prime is 21996407297. The next prime is 21996407333. The reversal of 21996407309 is 90370469912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 19782422500 + 2213984809 = 140650^2 + 47053^2 .

It is a cyclic number.

It is not a de Polignac number, because 21996407309 - 2²⁰ = 21995358733 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 (21996407509) 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, 207513224 + ... + 207513329.

It is an arithmetic number, because the mean of its divisors is an integer number (5602858479).

Almost surely, 2^21996407309 is an apocalyptic number.

It is an amenable number.

21996407309 is a deficient number, since it is larger than the sum of its proper divisors (415026607).

21996407309 is an equidigital number, since it uses as much as digits as its factorization.

21996407309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415026606.

The product of its (nonzero) digits is 734832, while the sum is 50.

The spelling of 21996407309 in words is "twenty-one billion, nine hundred ninety-six million, four hundred seven thousand, three hundred nine".