21204156529 has 2 divisors, whose sum is σ = 21204156530. Its totient is φ = 21204156528.

The previous prime is 21204156511. The next prime is 21204156629. The reversal of 21204156529 is 92565140212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21184220304 + 19936225 = 145548^2 + 4465^2 .

It is a cyclic number.

It is not a de Polignac number, because 21204156529 - 2¹⁷ = 21204025457 is a prime.

It is not a weakly prime, because it can be changed into another prime (21204156629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602078264 + 10602078265.

It is an arithmetic number, because the mean of its divisors is an integer number (10602078265).

Almost surely, 2^21204156529 is an apocalyptic number.

It is an amenable number.

21204156529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204156529 is an equidigital number, since it uses as much as digits as its factorization.

21204156529 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 37.

The spelling of 21204156529 in words is "twenty-one billion, two hundred four million, one hundred fifty-six thousand, five hundred twenty-nine".