19507449721 has 2 divisors, whose sum is σ = 19507449722. Its totient is φ = 19507449720.

The previous prime is 19507449667. The next prime is 19507449743. The reversal of 19507449721 is 12794470591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12620275600 + 6887174121 = 112340^2 + 82989^2 .

It is a cyclic number.

It is not a de Polignac number, because 19507449721 - 2¹⁹ = 19506925433 is a prime.

It is not a weakly prime, because it can be changed into another prime (19507449791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9753724860 + 9753724861.

It is an arithmetic number, because the mean of its divisors is an integer number (9753724861).

Almost surely, 2^19507449721 is an apocalyptic number.

It is an amenable number.

19507449721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19507449721 is an equidigital number, since it uses as much as digits as its factorization.

19507449721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 635040, while the sum is 49.

The spelling of 19507449721 in words is "nineteen billion, five hundred seven million, four hundred forty-nine thousand, seven hundred twenty-one".