21897580877 has 2 divisors, whose sum is σ = 21897580878. Its totient is φ = 21897580876.

The previous prime is 21897580843. The next prime is 21897580889. The reversal of 21897580877 is 77808579812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17142926761 + 4754654116 = 130931^2 + 68954^2 .

It is a cyclic number.

It is not a de Polignac number, because 21897580877 - 2¹² = 21897576781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21897582877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10948790438 + 10948790439.

It is an arithmetic number, because the mean of its divisors is an integer number (10948790439).

Almost surely, 2^21897580877 is an apocalyptic number.

It is an amenable number.

21897580877 is a deficient number, since it is larger than the sum of its proper divisors (1).

21897580877 is an equidigital number, since it uses as much as digits as its factorization.

21897580877 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15805440, while the sum is 62.

The spelling of 21897580877 in words is "twenty-one billion, eight hundred ninety-seven million, five hundred eighty thousand, eight hundred seventy-seven".