21194729 has 4 divisors (see below), whose sum is σ = 21206340. Its totient is φ = 21183120.

The previous prime is 21194689. The next prime is 21194773. The reversal of 21194729 is 92749112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 3115225 + 18079504 = 1765^2 + 4252^2 .

It is a cyclic number.

It is not a de Polignac number, because 21194729 - 2²⁰ = 20146153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21194029) 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, 2402 + ... + 6939.

It is an arithmetic number, because the mean of its divisors is an integer number (5301585).

Almost surely, 2^21194729 is an apocalyptic number.

It is an amenable number.

21194729 is a deficient number, since it is larger than the sum of its proper divisors (11611).

21194729 is an equidigital number, since it uses as much as digits as its factorization.

21194729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11610.

The product of its digits is 9072, while the sum is 35.

The square root of 21194729 is about 4603.7733436823. The cubic root of 21194729 is about 276.7425612340.

The spelling of 21194729 in words is "twenty-one million, one hundred ninety-four thousand, seven hundred twenty-nine".