21872750021 has 4 divisors (see below), whose sum is σ = 21877459500. Its totient is φ = 21868040544.

The previous prime is 21872749963. The next prime is 21872750033. The reversal of 21872750021 is 12005727812.

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 19262664100 + 2610085921 = 138790^2 + 51089^2 .

It is a cyclic number.

It is not a de Polignac number, because 21872750021 - 2³⁴ = 4692880837 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 (21872750051) 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, 2347766 + ... + 2357063.

It is an arithmetic number, because the mean of its divisors is an integer number (5469364875).

Almost surely, 2^21872750021 is an apocalyptic number.

It is an amenable number.

21872750021 is a deficient number, since it is larger than the sum of its proper divisors (4709479).

21872750021 is an equidigital number, since it uses as much as digits as its factorization.

21872750021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4709478.

The product of its (nonzero) digits is 15680, while the sum is 35.

The spelling of 21872750021 in words is "twenty-one billion, eight hundred seventy-two million, seven hundred fifty thousand, twenty-one".