20491087 has 4 divisors (see below), whose sum is σ = 20507040. Its totient is φ = 20475136.

The previous prime is 20491073. The next prime is 20491109. The reversal of 20491087 is 78019402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20491087 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20491057) 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, 5863 + ... + 8680.

It is an arithmetic number, because the mean of its divisors is an integer number (5126760).

Almost surely, 2^20491087 is an apocalyptic number.

20491087 is a deficient number, since it is larger than the sum of its proper divisors (15953).

20491087 is a wasteful number, since it uses less digits than its factorization.

20491087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15952.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20491087 is about 4526.7081858675. The cubic root of 20491087 is about 273.6455136642.

It can be divided in two parts, 2049 and 1087, that added together give a square (3136 = 56²).

The spelling of 20491087 in words is "twenty million, four hundred ninety-one thousand, eighty-seven".