19397987 has 4 divisors (see below), whose sum is σ = 22169136. Its totient is φ = 16626840.

The previous prime is 19397977. The next prime is 19398019. The reversal of 19397987 is 78979391.

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 19397987 - 2¹⁸ = 19135843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19397927) 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, 1385564 + ... + 1385577.

It is an arithmetic number, because the mean of its divisors is an integer number (5542284).

Almost surely, 2^19397987 is an apocalyptic number.

19397987 is a deficient number, since it is larger than the sum of its proper divisors (2771149).

19397987 is an equidigital number, since it uses as much as digits as its factorization.

19397987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2771148.

The product of its digits is 857304, while the sum is 53.

The square root of 19397987 is about 4404.3145891273. The cubic root of 19397987 is about 268.6904442036.

The spelling of 19397987 in words is "nineteen million, three hundred ninety-seven thousand, nine hundred eighty-seven".