987899921 has 2 divisors, whose sum is σ = 987899922. Its totient is φ = 987899920.

The previous prime is 987899917. The next prime is 987899923. The reversal of 987899921 is 129998789.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 530795521 + 457104400 = 23039^2 + 21380^2 .

It is a cyclic number.

It is not a de Polignac number, because 987899921 - 2² = 987899917 is a prime.

Together with 987899923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (987899923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 493949960 + 493949961.

It is an arithmetic number, because the mean of its divisors is an integer number (493949961).

Almost surely, 2^987899921 is an apocalyptic number.

It is an amenable number.

987899921 is a deficient number, since it is larger than the sum of its proper divisors (1).

987899921 is an equidigital number, since it uses as much as digits as its factorization.

987899921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5878656, while the sum is 62.

The square root of 987899921 is about 31430.8752821171. The cubic root of 987899921 is about 995.9502620953.

The spelling of 987899921 in words is "nine hundred eighty-seven million, eight hundred ninety-nine thousand, nine hundred twenty-one".