1987813 has 4 divisors (see below), whose sum is σ = 2051968. Its totient is φ = 1923660.

The previous prime is 1987789. The next prime is 1987819. The reversal of 1987813 is 3187891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1987813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987819) 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, 32031 + ... + 32092.

It is an arithmetic number, because the mean of its divisors is an integer number (512992).

2^1987813 is an apocalyptic number.

It is an amenable number.

1987813 is a deficient number, since it is larger than the sum of its proper divisors (64155).

1987813 is an equidigital number, since it uses as much as digits as its factorization.

1987813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64154.

The product of its digits is 12096, while the sum is 37.

The square root of 1987813 is about 1409.8982232771. The cubic root of 1987813 is about 125.7356724609.

It can be divided in two parts, 19878 and 13, that added together give a palindrome (19891).

The spelling of 1987813 in words is "one million, nine hundred eighty-seven thousand, eight hundred thirteen".