61745807891 has 2 divisors, whose sum is σ = 61745807892. Its totient is φ = 61745807890.

The previous prime is 61745807887. The next prime is 61745807911. The reversal of 61745807891 is 19870854716.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61745807891 - 2² = 61745807887 is a prime.

It is a super-2 number, since 2×61745807891² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (61745807861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30872903945 + 30872903946.

It is an arithmetic number, because the mean of its divisors is an integer number (30872903946).

Almost surely, 2^61745807891 is an apocalyptic number.

61745807891 is a deficient number, since it is larger than the sum of its proper divisors (1).

61745807891 is an equidigital number, since it uses as much as digits as its factorization.

61745807891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3386880, while the sum is 56.

The spelling of 61745807891 in words is "sixty-one billion, seven hundred forty-five million, eight hundred seven thousand, eight hundred ninety-one".