19556499997 has 2 divisors, whose sum is σ = 19556499998. Its totient is φ = 19556499996.

The previous prime is 19556499973. The next prime is 19556500027. The reversal of 19556499997 is 79999465591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17711883396 + 1844616601 = 133086^2 + 42949^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19556499997 is a prime.

It is a super-2 number, since 2×19556499997² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19556499397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9778249998 + 9778249999.

It is an arithmetic number, because the mean of its divisors is an integer number (9778249999).

Almost surely, 2^19556499997 is an apocalyptic number.

It is an amenable number.

19556499997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19556499997 is an equidigital number, since it uses as much as digits as its factorization.

19556499997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248005800, while the sum is 73.

The spelling of 19556499997 in words is "nineteen billion, five hundred fifty-six million, four hundred ninety-nine thousand, nine hundred ninety-seven".