61778472517 has 2 divisors, whose sum is σ = 61778472518. Its totient is φ = 61778472516.

The previous prime is 61778472487. The next prime is 61778472551. The reversal of 61778472517 is 71527487716.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37641432196 + 24137040321 = 194014^2 + 155361^2 .

It is a cyclic number.

It is not a de Polignac number, because 61778472517 - 2¹⁹ = 61777948229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61778472817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30889236258 + 30889236259.

It is an arithmetic number, because the mean of its divisors is an integer number (30889236259).

Almost surely, 2^61778472517 is an apocalyptic number.

It is an amenable number.

61778472517 is a deficient number, since it is larger than the sum of its proper divisors (1).

61778472517 is an equidigital number, since it uses as much as digits as its factorization.

61778472517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4609920, while the sum is 55.

The spelling of 61778472517 in words is "sixty-one billion, seven hundred seventy-eight million, four hundred seventy-two thousand, five hundred seventeen".