61591997 has 2 divisors, whose sum is σ = 61591998. Its totient is φ = 61591996.

The previous prime is 61591991. The next prime is 61592017. The reversal of 61591997 is 79919516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55145476 + 6446521 = 7426^2 + 2539^2 .

It is a cyclic number.

It is not a de Polignac number, because 61591997 - 2¹⁰ = 61590973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61591991) 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, 30795998 + 30795999.

It is an arithmetic number, because the mean of its divisors is an integer number (30795999).

Almost surely, 2^61591997 is an apocalyptic number.

It is an amenable number.

61591997 is a deficient number, since it is larger than the sum of its proper divisors (1).

61591997 is an equidigital number, since it uses as much as digits as its factorization.

61591997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 153090, while the sum is 47.

The square root of 61591997 is about 7848.0568932698. The cubic root of 61591997 is about 394.9190604868.

The spelling of 61591997 in words is "sixty-one million, five hundred ninety-one thousand, nine hundred ninety-seven".