18720587 has 4 divisors (see below), whose sum is σ = 19821816. Its totient is φ = 17619360.

The previous prime is 18720577. The next prime is 18720589. The reversal of 18720587 is 78502781.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18720587 - 2⁴ = 18720571 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18720587.

It is not an unprimeable number, because it can be changed into a prime (18720589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 550589 + ... + 550622.

It is an arithmetic number, because the mean of its divisors is an integer number (4955454).

Almost surely, 2^18720587 is an apocalyptic number.

18720587 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

18720587 is a deficient number, since it is larger than the sum of its proper divisors (1101229).

18720587 is a wasteful number, since it uses less digits than its factorization.

18720587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1101228.

The product of its (nonzero) digits is 31360, while the sum is 38.

The square root of 18720587 is about 4326.7293652365. The cubic root of 18720587 is about 265.5256541426.

The spelling of 18720587 in words is "eighteen million, seven hundred twenty thousand, five hundred eighty-seven".