19987265 has 4 divisors (see below), whose sum is σ = 23984724. Its totient is φ = 15989808.

The previous prime is 19987229. The next prime is 19987271. The reversal of 19987265 is 56278991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56278991 = 199 ⋅282809.

It can be written as a sum of positive squares in 2 ways, for example, as 14077504 + 5909761 = 3752^2 + 2431^2 .

It is a cyclic number.

It is not a de Polignac number, because 19987265 - 2²⁴ = 3210049 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1998722 + ... + 1998731.

It is an arithmetic number, because the mean of its divisors is an integer number (5996181).

Almost surely, 2^19987265 is an apocalyptic number.

It is an amenable number.

19987265 is a deficient number, since it is larger than the sum of its proper divisors (3997459).

19987265 is an equidigital number, since it uses as much as digits as its factorization.

19987265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3997458.

The product of its digits is 272160, while the sum is 47.

The square root of 19987265 is about 4470.7119119890. The cubic root of 19987265 is about 271.3841359128.

The spelling of 19987265 in words is "nineteen million, nine hundred eighty-seven thousand, two hundred sixty-five".