2181987 has 24 divisors (see below), whose sum is σ = 3354624. Its totient is φ = 1363824.

The previous prime is 2181973. The next prime is 2182007. The reversal of 2181987 is 7891812.

It is not a de Polignac number, because 2181987 - 2⁸ = 2181731 is a prime.

It is a super-2 number, since 2×2181987² = 9522134536338, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (2181937) 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, 17118 + ... + 17244.

It is an arithmetic number, because the mean of its divisors is an integer number (139776).

2^2181987 is an apocalyptic number.

2181987 is a deficient number, since it is larger than the sum of its proper divisors (1172637).

2181987 is a wasteful number, since it uses less digits than its factorization.

2181987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239 (or 236 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 2181987 is about 1477.1550358713. The cubic root of 2181987 is about 129.7032085390.

The spelling of 2181987 in words is "two million, one hundred eighty-one thousand, nine hundred eighty-seven".