21872886661 has 2 divisors, whose sum is σ = 21872886662. Its totient is φ = 21872886660.

The previous prime is 21872886551. The next prime is 21872886671. The reversal of 21872886661 is 16668827812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11973830625 + 9899056036 = 109425^2 + 99494^2 .

It is a cyclic number.

It is not a de Polignac number, because 21872886661 - 2²³ = 21864498053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21872886671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936443330 + 10936443331.

It is an arithmetic number, because the mean of its divisors is an integer number (10936443331).

Almost surely, 2^21872886661 is an apocalyptic number.

It is an amenable number.

21872886661 is a deficient number, since it is larger than the sum of its proper divisors (1).

21872886661 is an equidigital number, since it uses as much as digits as its factorization.

21872886661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3096576, while the sum is 55.

The spelling of 21872886661 in words is "twenty-one billion, eight hundred seventy-two million, eight hundred eighty-six thousand, six hundred sixty-one".