61939991 has 2 divisors, whose sum is σ = 61939992. Its totient is φ = 61939990.

The previous prime is 61939979. The next prime is 61940003. The reversal of 61939991 is 19993916.

It is a balanced prime because it is at equal distance from previous prime (61939979) and next prime (61940003).

It is a cyclic number.

It is not a de Polignac number, because 61939991 - 2²² = 57745687 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 (61939931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30969995 + 30969996.

It is an arithmetic number, because the mean of its divisors is an integer number (30969996).

Almost surely, 2^61939991 is an apocalyptic number.

61939991 is a deficient number, since it is larger than the sum of its proper divisors (1).

61939991 is an equidigital number, since it uses as much as digits as its factorization.

61939991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 118098, while the sum is 47.

The square root of 61939991 is about 7870.1963762031. The cubic root of 61939991 is about 395.6614266744.

The spelling of 61939991 in words is "sixty-one million, nine hundred thirty-nine thousand, nine hundred ninety-one".