21180087 has 6 divisors (see below), whose sum is σ = 30593472. Its totient is φ = 14120052.

The previous prime is 21180083. The next prime is 21180101. The reversal of 21180087 is 78008112.

It is not a de Polignac number, because 21180087 - 2² = 21180083 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21180087.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21180083) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1176663 + ... + 1176680.

It is an arithmetic number, because the mean of its divisors is an integer number (5098912).

Almost surely, 2^21180087 is an apocalyptic number.

21180087 is a deficient number, since it is larger than the sum of its proper divisors (9413385).

21180087 is a wasteful number, since it uses less digits than its factorization.

21180087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2353349 (or 2353346 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 21180087 is about 4602.1828516477. The cubic root of 21180087 is about 276.6788190014.

Adding to 21180087 its reverse (78008112), we get a palindrome (99188199).

The spelling of 21180087 in words is "twenty-one million, one hundred eighty thousand, eighty-seven".