20491019817 has 4 divisors (see below), whose sum is σ = 27321359760. Its totient is φ = 13660679876.

The previous prime is 20491019771. The next prime is 20491019833. The reversal of 20491019817 is 71891019402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20491019817 - 2¹¹ = 20491017769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20491015817) 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, 3415169967 + ... + 3415169972.

It is an arithmetic number, because the mean of its divisors is an integer number (6830339940).

Almost surely, 2^20491019817 is an apocalyptic number.

It is an amenable number.

20491019817 is a deficient number, since it is larger than the sum of its proper divisors (6830339943).

20491019817 is an equidigital number, since it uses as much as digits as its factorization.

20491019817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6830339942.

The product of its (nonzero) digits is 36288, while the sum is 42.

The spelling of 20491019817 in words is "twenty billion, four hundred ninety-one million, nineteen thousand, eight hundred seventeen".