61581330393991 has 2 divisors, whose sum is σ = 61581330393992. Its totient is φ = 61581330393990.

The previous prime is 61581330393953. The next prime is 61581330394037. The reversal of 61581330393991 is 19939303318516.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61581330393991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61581330313991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30790665196995 + 30790665196996.

It is an arithmetic number, because the mean of its divisors is an integer number (30790665196996).

Almost surely, 2^{61581330393991} is an apocalyptic number.

61581330393991 is a deficient number, since it is larger than the sum of its proper divisors (1).

61581330393991 is an equidigital number, since it uses as much as digits as its factorization.

61581330393991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14171760, while the sum is 61.

The spelling of 61581330393991 in words is "sixty-one trillion, five hundred eighty-one billion, three hundred thirty million, three hundred ninety-three thousand, nine hundred ninety-one".