19870091 has 4 divisors (see below), whose sum is σ = 20734032. Its totient is φ = 19006152.

The previous prime is 19870063. The next prime is 19870099. The reversal of 19870091 is 19007891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19007891 = 7 ⋅2715413.

It is a cyclic number.

It is not a de Polignac number, because 19870091 - 2⁶ = 19870027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19870099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 431936 + ... + 431981.

It is an arithmetic number, because the mean of its divisors is an integer number (5183508).

Almost surely, 2^19870091 is an apocalyptic number.

19870091 is a deficient number, since it is larger than the sum of its proper divisors (863941).

19870091 is an equidigital number, since it uses as much as digits as its factorization.

19870091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 863940.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 19870091 is about 4457.5880249301. The cubic root of 19870091 is about 270.8527724325.

The spelling of 19870091 in words is "nineteen million, eight hundred seventy thousand, ninety-one".