21104729 has 2 divisors, whose sum is σ = 21104730. Its totient is φ = 21104728.

The previous prime is 21104723. The next prime is 21104747. The reversal of 21104729 is 92740112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13690000 + 7414729 = 3700^2 + 2723^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21104729 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21104698 and 21104707.

It is not a weakly prime, because it can be changed into another prime (21104723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552364 + 10552365.

It is an arithmetic number, because the mean of its divisors is an integer number (10552365).

Almost surely, 2^21104729 is an apocalyptic number.

It is an amenable number.

21104729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21104729 is an equidigital number, since it uses as much as digits as its factorization.

21104729 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21104729 is about 4593.9883543605. The cubic root of 21104729 is about 276.3502912472.

The spelling of 21104729 in words is "twenty-one million, one hundred four thousand, seven hundred twenty-nine".