61799721397 has 2 divisors, whose sum is σ = 61799721398. Its totient is φ = 61799721396.

The previous prime is 61799721377. The next prime is 61799721413. The reversal of 61799721397 is 79312799716.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59484283236 + 2315438161 = 243894^2 + 48119^2 .

It is a cyclic number.

It is not a de Polignac number, because 61799721397 - 2³⁵ = 27439983029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61799721377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30899860698 + 30899860699.

It is an arithmetic number, because the mean of its divisors is an integer number (30899860699).

Almost surely, 2^61799721397 is an apocalyptic number.

It is an amenable number.

61799721397 is a deficient number, since it is larger than the sum of its proper divisors (1).

61799721397 is an equidigital number, since it uses as much as digits as its factorization.

61799721397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9001692, while the sum is 61.

The spelling of 61799721397 in words is "sixty-one billion, seven hundred ninety-nine million, seven hundred twenty-one thousand, three hundred ninety-seven".