21990362729 has 2 divisors, whose sum is σ = 21990362730. Its totient is φ = 21990362728.

The previous prime is 21990362623. The next prime is 21990362731. The reversal of 21990362729 is 92726309912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13701170704 + 8289192025 = 117052^2 + 91045^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21990362729 is a prime.

Together with 21990362731, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21990352729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10995181364 + 10995181365.

It is an arithmetic number, because the mean of its divisors is an integer number (10995181365).

Almost surely, 2^21990362729 is an apocalyptic number.

It is an amenable number.

21990362729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21990362729 is an equidigital number, since it uses as much as digits as its factorization.

21990362729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 734832, while the sum is 50.

The spelling of 21990362729 in words is "twenty-one billion, nine hundred ninety million, three hundred sixty-two thousand, seven hundred twenty-nine".