21504398737 has 2 divisors, whose sum is σ = 21504398738. Its totient is φ = 21504398736.

The previous prime is 21504398731. The next prime is 21504398767. The reversal of 21504398737 is 73789340512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18149208961 + 3355189776 = 134719^2 + 57924^2 .

It is a cyclic number.

It is not a de Polignac number, because 21504398737 - 2²⁷ = 21370181009 is a prime.

It is not a weakly prime, because it can be changed into another prime (21504398731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752199368 + 10752199369.

It is an arithmetic number, because the mean of its divisors is an integer number (10752199369).

Almost surely, 2^21504398737 is an apocalyptic number.

It is an amenable number.

21504398737 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504398737 is an equidigital number, since it uses as much as digits as its factorization.

21504398737 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1270080, while the sum is 49.

The spelling of 21504398737 in words is "twenty-one billion, five hundred four million, three hundred ninety-eight thousand, seven hundred thirty-seven".