19355013721 has 2 divisors, whose sum is σ = 19355013722. Its totient is φ = 19355013720.

The previous prime is 19355013709. The next prime is 19355013737. The reversal of 19355013721 is 12731055391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18767630025 + 587383696 = 136995^2 + 24236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19355013721 is a prime.

It is a super-2 number, since 2×19355013721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (19355013121) 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, 9677506860 + 9677506861.

It is an arithmetic number, because the mean of its divisors is an integer number (9677506861).

Almost surely, 2^19355013721 is an apocalyptic number.

It is an amenable number.

19355013721 is a deficient number, since it is larger than the sum of its proper divisors (1).

19355013721 is an equidigital number, since it uses as much as digits as its factorization.

19355013721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 28350, while the sum is 37.

The spelling of 19355013721 in words is "nineteen billion, three hundred fifty-five million, thirteen thousand, seven hundred twenty-one".