21497963171 has 4 divisors (see below), whose sum is σ = 21610518144. Its totient is φ = 21385408200.

The previous prime is 21497963153. The next prime is 21497963189. The reversal of 21497963171 is 17136979412.

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

It is an interprime number because it is at equal distance from previous prime (21497963153) and next prime (21497963189).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21497963171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21497963131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56277200 + ... + 56277581.

It is an arithmetic number, because the mean of its divisors is an integer number (5402629536).

Almost surely, 2^21497963171 is an apocalyptic number.

21497963171 is a deficient number, since it is larger than the sum of its proper divisors (112554973).

21497963171 is a wasteful number, since it uses less digits than its factorization.

21497963171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112554972.

The product of its digits is 571536, while the sum is 50.

The spelling of 21497963171 in words is "twenty-one billion, four hundred ninety-seven million, nine hundred sixty-three thousand, one hundred seventy-one".