61891543997 has 2 divisors, whose sum is σ = 61891543998. Its totient is φ = 61891543996.

The previous prime is 61891543991. The next prime is 61891544069. The reversal of 61891543997 is 79934519816.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61827319801 + 64224196 = 248651^2 + 8014^2 .

It is a cyclic number.

It is not a de Polignac number, because 61891543997 - 2⁴ = 61891543981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61891543991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30945771998 + 30945771999.

It is an arithmetic number, because the mean of its divisors is an integer number (30945771999).

Almost surely, 2^61891543997 is an apocalyptic number.

It is an amenable number.

61891543997 is a deficient number, since it is larger than the sum of its proper divisors (1).

61891543997 is an equidigital number, since it uses as much as digits as its factorization.

61891543997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 14696640, while the sum is 62.

The spelling of 61891543997 in words is "sixty-one billion, eight hundred ninety-one million, five hundred forty-three thousand, nine hundred ninety-seven".