21497805479 has 4 divisors (see below), whose sum is σ = 22022142240. Its totient is φ = 20973468720.

The previous prime is 21497805421. The next prime is 21497805487. The reversal of 21497805479 is 97450879412.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21497805479 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 (21497805419) 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, 262168319 + ... + 262168400.

It is an arithmetic number, because the mean of its divisors is an integer number (5505535560).

Almost surely, 2^21497805479 is an apocalyptic number.

21497805479 is a deficient number, since it is larger than the sum of its proper divisors (524336761).

21497805479 is an equidigital number, since it uses as much as digits as its factorization.

21497805479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524336760.

The product of its (nonzero) digits is 5080320, while the sum is 56.

The spelling of 21497805479 in words is "twenty-one billion, four hundred ninety-seven million, eight hundred five thousand, four hundred seventy-nine".