20491539 has 4 divisors (see below), whose sum is σ = 27322056. Its totient is φ = 13661024.

The previous prime is 20491489. The next prime is 20491561. The reversal of 20491539 is 93519402.

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 20491539 - 2⁸ = 20491283 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20491039) 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, 3415254 + ... + 3415259.

It is an arithmetic number, because the mean of its divisors is an integer number (6830514).

Almost surely, 2^20491539 is an apocalyptic number.

20491539 is a deficient number, since it is larger than the sum of its proper divisors (6830517).

20491539 is an equidigital number, since it uses as much as digits as its factorization.

20491539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6830516.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 20491539 is about 4526.7581114966. The cubic root of 20491539 is about 273.6475257075.

The spelling of 20491539 in words is "twenty million, four hundred ninety-one thousand, five hundred thirty-nine".