18987897 has 32 divisors (see below), whose sum is σ = 27934720. Its totient is φ = 11430720.

The previous prime is 18987889. The next prime is 18987907. The reversal of 18987897 is 79878981.

It is not a de Polignac number, because 18987897 - 2³ = 18987889 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18987877) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 149448 + ... + 149574.

It is an arithmetic number, because the mean of its divisors is an integer number (872960).

Almost surely, 2^18987897 is an apocalyptic number.

It is an amenable number.

18987897 is a deficient number, since it is larger than the sum of its proper divisors (8946823).

18987897 is a wasteful number, since it uses less digits than its factorization.

18987897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253.

The product of its digits is 2032128, while the sum is 57.

The square root of 18987897 is about 4357.5104130685. The cubic root of 18987897 is about 266.7834937757.

It can be divided in two parts, 1 and 8987897, that added together give a palindrome (8987898).

The spelling of 18987897 in words is "eighteen million, nine hundred eighty-seven thousand, eight hundred ninety-seven".