21690867589 has 2 divisors, whose sum is σ = 21690867590. Its totient is φ = 21690867588.

The previous prime is 21690867581. The next prime is 21690867593. The reversal of 21690867589 is 98576809612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20893257025 + 797610564 = 144545^2 + 28242^2 .

It is a cyclic number.

It is not a de Polignac number, because 21690867589 - 2³ = 21690867581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21690867581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10845433794 + 10845433795.

It is an arithmetic number, because the mean of its divisors is an integer number (10845433795).

Almost surely, 2^21690867589 is an apocalyptic number.

It is an amenable number.

21690867589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21690867589 is an equidigital number, since it uses as much as digits as its factorization.

21690867589 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13063680, while the sum is 61.

The spelling of 21690867589 in words is "twenty-one billion, six hundred ninety million, eight hundred sixty-seven thousand, five hundred eighty-nine".