21192388729 has 4 divisors (see below), whose sum is σ = 21219317584. Its totient is φ = 21165459876.

The previous prime is 21192388699. The next prime is 21192388757. The reversal of 21192388729 is 92788329112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21192388729 - 2⁵ = 21192388697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21192388769) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13463247 + ... + 13464820.

It is an arithmetic number, because the mean of its divisors is an integer number (5304829396).

Almost surely, 2^21192388729 is an apocalyptic number.

It is an amenable number.

21192388729 is a deficient number, since it is larger than the sum of its proper divisors (26928855).

21192388729 is an equidigital number, since it uses as much as digits as its factorization.

21192388729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26928854.

The product of its digits is 870912, while the sum is 52.

The spelling of 21192388729 in words is "twenty-one billion, one hundred ninety-two million, three hundred eighty-eight thousand, seven hundred twenty-nine".