61691999 has 2 divisors, whose sum is σ = 61692000. Its totient is φ = 61691998.

The previous prime is 61691983. The next prime is 61692013. The reversal of 61691999 is 99919616.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 61691999 - 2⁴ = 61691983 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61691909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30845999 + 30846000.

It is an arithmetic number, because the mean of its divisors is an integer number (30846000).

Almost surely, 2^61691999 is an apocalyptic number.

61691999 is a deficient number, since it is larger than the sum of its proper divisors (1).

61691999 is an equidigital number, since it uses as much as digits as its factorization.

61691999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 236196, while the sum is 50.

The square root of 61691999 is about 7854.4254404762. The cubic root of 61691999 is about 395.1326777496.

The spelling of 61691999 in words is "sixty-one million, six hundred ninety-one thousand, nine hundred ninety-nine".