21039079729 has 4 divisors (see below), whose sum is σ = 21039441984. Its totient is φ = 21038717476.

The previous prime is 21039079697. The next prime is 21039079739. The reversal of 21039079729 is 92797093012.

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 21039079729 - 2⁵ = 21039079697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21039079739) 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, 72157 + ... + 217450.

It is an arithmetic number, because the mean of its divisors is an integer number (5259860496).

Almost surely, 2^21039079729 is an apocalyptic number.

It is an amenable number.

21039079729 is a deficient number, since it is larger than the sum of its proper divisors (362255).

21039079729 is an equidigital number, since it uses as much as digits as its factorization.

21039079729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362254.

The product of its (nonzero) digits is 428652, while the sum is 49.

The spelling of 21039079729 in words is "twenty-one billion, thirty-nine million, seventy-nine thousand, seven hundred twenty-nine".