821699987 has 2 divisors, whose sum is σ = 821699988. Its totient is φ = 821699986.

The previous prime is 821699939. The next prime is 821700017. The reversal of 821699987 is 789996128.

821699987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 821699987 - 2²⁴ = 804922771 is a prime.

It is not a weakly prime, because it can be changed into another prime (821699387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410849993 + 410849994.

It is an arithmetic number, because the mean of its divisors is an integer number (410849994).

Almost surely, 2^821699987 is an apocalyptic number.

821699987 is a deficient number, since it is larger than the sum of its proper divisors (1).

821699987 is an equidigital number, since it uses as much as digits as its factorization.

821699987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3919104, while the sum is 59.

The square root of 821699987 is about 28665.3098186641. The cubic root of 821699987 is about 936.6365333675.

The spelling of 821699987 in words is "eight hundred twenty-one million, six hundred ninety-nine thousand, nine hundred eighty-seven".