21936729169 has 2 divisors, whose sum is σ = 21936729170. Its totient is φ = 21936729168.

The previous prime is 21936729149. The next prime is 21936729179. The reversal of 21936729169 is 96192763912.

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., 21929759569 + 6969600 = 148087^2 + 2640^2 .

It is a cyclic number.

It is not a de Polignac number, because 21936729169 - 2⁷ = 21936729041 is a prime.

It is a super-2 number, since 2×21936729169² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21936729109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10968364584 + 10968364585.

It is an arithmetic number, because the mean of its divisors is an integer number (10968364585).

Almost surely, 2^21936729169 is an apocalyptic number.

It is an amenable number.

21936729169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21936729169 is an equidigital number, since it uses as much as digits as its factorization.

21936729169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2204496, while the sum is 55.

The spelling of 21936729169 in words is "twenty-one billion, nine hundred thirty-six million, seven hundred twenty-nine thousand, one hundred sixty-nine".