61891544069 has 2 divisors, whose sum is σ = 61891544070. Its totient is φ = 61891544068.

The previous prime is 61891543997. The next prime is 61891544087. The reversal of 61891544069 is 96044519816.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60705568225 + 1185975844 = 246385^2 + 34438^2 .

It is a cyclic number.

It is not a de Polignac number, because 61891544069 - 2¹² = 61891539973 is a prime.

It is a super-2 number, since 2×61891544069² (a number of 22 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 61891544069.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61891544369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30945772034 + 30945772035.

It is an arithmetic number, because the mean of its divisors is an integer number (30945772035).

Almost surely, 2^61891544069 is an apocalyptic number.

It is an amenable number.

61891544069 is a deficient number, since it is larger than the sum of its proper divisors (1).

61891544069 is an equidigital number, since it uses as much as digits as its factorization.

61891544069 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1866240, while the sum is 53.

The spelling of 61891544069 in words is "sixty-one billion, eight hundred ninety-one million, five hundred forty-four thousand, sixty-nine".