61518991 has 2 divisors, whose sum is σ = 61518992. Its totient is φ = 61518990.

The previous prime is 61518953. The next prime is 61519001. The reversal of 61518991 is 19981516.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 61518991 - 2¹¹ = 61516943 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 (61518091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30759495 + 30759496.

It is an arithmetic number, because the mean of its divisors is an integer number (30759496).

Almost surely, 2^61518991 is an apocalyptic number.

61518991 is a deficient number, since it is larger than the sum of its proper divisors (1).

61518991 is an equidigital number, since it uses as much as digits as its factorization.

61518991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 40.

The square root of 61518991 is about 7843.4042991548. The cubic root of 61518991 is about 394.7629641252.

The spelling of 61518991 in words is "sixty-one million, five hundred eighteen thousand, nine hundred ninety-one".