21908720473 has 4 divisors (see below), whose sum is σ = 21910958388. Its totient is φ = 21906482560.

The previous prime is 21908720453. The next prime is 21908720501. The reversal of 21908720473 is 37402780912.

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 4078993689 + 17829726784 = 63867^2 + 133528^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21908720473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21908720453) 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, 1104208 + ... + 1123873.

It is an arithmetic number, because the mean of its divisors is an integer number (5477739597).

Almost surely, 2^21908720473 is an apocalyptic number.

It is an amenable number.

21908720473 is a deficient number, since it is larger than the sum of its proper divisors (2237915).

21908720473 is an equidigital number, since it uses as much as digits as its factorization.

21908720473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2237914.

The product of its (nonzero) digits is 169344, while the sum is 43.

The spelling of 21908720473 in words is "twenty-one billion, nine hundred eight million, seven hundred twenty thousand, four hundred seventy-three".