21504061729 has 2 divisors, whose sum is σ = 21504061730. Its totient is φ = 21504061728.

The previous prime is 21504061697. The next prime is 21504061771. The reversal of 21504061729 is 92716040512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17487417600 + 4016644129 = 132240^2 + 63377^2 .

It is a cyclic number.

It is not a de Polignac number, because 21504061729 - 2⁵ = 21504061697 is a prime.

It is not a weakly prime, because it can be changed into another prime (21504061529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752030864 + 10752030865.

It is an arithmetic number, because the mean of its divisors is an integer number (10752030865).

Almost surely, 2^21504061729 is an apocalyptic number.

It is an amenable number.

21504061729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504061729 is an equidigital number, since it uses as much as digits as its factorization.

21504061729 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30240, while the sum is 37.

The spelling of 21504061729 in words is "twenty-one billion, five hundred four million, sixty-one thousand, seven hundred twenty-nine".