19551577261 has 2 divisors, whose sum is σ = 19551577262. Its totient is φ = 19551577260.

The previous prime is 19551577189. The next prime is 19551577267. The reversal of 19551577261 is 16277515591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19430687236 + 120890025 = 139394^2 + 10995^2 .

It is a cyclic number.

It is not a de Polignac number, because 19551577261 - 2¹¹ = 19551575213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19551577267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9775788630 + 9775788631.

It is an arithmetic number, because the mean of its divisors is an integer number (9775788631).

Almost surely, 2^19551577261 is an apocalyptic number.

It is an amenable number.

19551577261 is a deficient number, since it is larger than the sum of its proper divisors (1).

19551577261 is an equidigital number, since it uses as much as digits as its factorization.

19551577261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 661500, while the sum is 49.

The spelling of 19551577261 in words is "nineteen billion, five hundred fifty-one million, five hundred seventy-seven thousand, two hundred sixty-one".