21725256671 has 16 divisors (see below), whose sum is σ = 23085388800. Its totient is φ = 20402704608.

The previous prime is 21725256647. The next prime is 21725256673. The reversal of 21725256671 is 17665252712.

It is a cyclic number.

It is not a de Polignac number, because 21725256671 - 2¹⁰ = 21725255647 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 (21725256673) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 291845 + ... + 358641.

It is an arithmetic number, because the mean of its divisors is an integer number (1442836800).

Almost surely, 2^21725256671 is an apocalyptic number.

21725256671 is a deficient number, since it is larger than the sum of its proper divisors (1360132129).

21725256671 is a wasteful number, since it uses less digits than its factorization.

21725256671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67078.

The product of its digits is 352800, while the sum is 44.

The spelling of 21725256671 in words is "twenty-one billion, seven hundred twenty-five million, two hundred fifty-six thousand, six hundred seventy-one".