21725502161 has 4 divisors (see below), whose sum is σ = 23700547824. Its totient is φ = 19750456500.

The previous prime is 21725502133. The next prime is 21725502167. The reversal of 21725502161 is 16120552712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21725502161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21725502167) 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, 987522815 + ... + 987522836.

It is an arithmetic number, because the mean of its divisors is an integer number (5925136956).

Almost surely, 2^21725502161 is an apocalyptic number.

It is an amenable number.

21725502161 is a deficient number, since it is larger than the sum of its proper divisors (1975045663).

21725502161 is a wasteful number, since it uses less digits than its factorization.

21725502161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1975045662.

The product of its (nonzero) digits is 8400, while the sum is 32.

The spelling of 21725502161 in words is "twenty-one billion, seven hundred twenty-five million, five hundred two thousand, one hundred sixty-one".