21565429189 has 2 divisors, whose sum is σ = 21565429190. Its totient is φ = 21565429188.

The previous prime is 21565429163. The next prime is 21565429213. The reversal of 21565429189 is 98192456512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21274556164 + 290873025 = 145858^2 + 17055^2 .

It is a cyclic number.

It is not a de Polignac number, because 21565429189 - 2²³ = 21557040581 is a prime.

It is a super-2 number, since 2×21565429189² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21565459189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10782714594 + 10782714595.

It is an arithmetic number, because the mean of its divisors is an integer number (10782714595).

Almost surely, 2^21565429189 is an apocalyptic number.

It is an amenable number.

21565429189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21565429189 is an equidigital number, since it uses as much as digits as its factorization.

21565429189 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1555200, while the sum is 52.

It can be divided in two parts, 2156 and 5429189, that added together give a palindrome (5431345).

The spelling of 21565429189 in words is "twenty-one billion, five hundred sixty-five million, four hundred twenty-nine thousand, one hundred eighty-nine".