7921687 has 2 divisors, whose sum is σ = 7921688. Its totient is φ = 7921686.

The previous prime is 7921679. The next prime is 7921691. The reversal of 7921687 is 7861297.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 7921687 - 2³ = 7921679 is a prime.

It is an Ulam number.

7921687 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7921607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3960843 + 3960844.

It is an arithmetic number, because the mean of its divisors is an integer number (3960844).

Almost surely, 2^7921687 is an apocalyptic number.

7921687 is a deficient number, since it is larger than the sum of its proper divisors (1).

7921687 is an equidigital number, since it uses as much as digits as its factorization.

7921687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 42336, while the sum is 40.

The square root of 7921687 is about 2814.5491646088. The cubic root of 7921687 is about 199.3452505213.

The spelling of 7921687 in words is "seven million, nine hundred twenty-one thousand, six hundred eighty-seven".