7681991 has 2 divisors, whose sum is σ = 7681992. Its totient is φ = 7681990.

The previous prime is 7681969. The next prime is 7682021. The reversal of 7681991 is 1991867.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7681991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7681591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3840995 + 3840996.

It is an arithmetic number, because the mean of its divisors is an integer number (3840996).

Almost surely, 2^7681991 is an apocalyptic number.

7681991 is a deficient number, since it is larger than the sum of its proper divisors (1).

7681991 is an equidigital number, since it uses as much as digits as its factorization.

7681991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 41.

The square root of 7681991 is about 2771.6404889523. The cubic root of 7681991 is about 197.3140138769.

The spelling of 7681991 in words is "seven million, six hundred eighty-one thousand, nine hundred ninety-one".