987921 has 24 divisors (see below), whose sum is σ = 1651104. Its totient is φ = 562560.

The previous prime is 987913. The next prime is 987929. The reversal of 987921 is 129789.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (987913) and next prime (987929).

It is not a de Polignac number, because 987921 - 2³ = 987913 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (987929) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1390 + ... + 1976.

It is an arithmetic number, because the mean of its divisors is an integer number (68796).

2⁹⁸⁷⁹²¹ is an apocalyptic number.

It is an amenable number.

987921 is a deficient number, since it is larger than the sum of its proper divisors (663183).

987921 is a wasteful number, since it uses less digits than its factorization.

987921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 621 (or 618 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 987921 is about 993.9421512342. The cubic root of 987921 is about 99.5957345635.

The spelling of 987921 in words is "nine hundred eighty-seven thousand, nine hundred twenty-one".