20818916731 has 4 divisors (see below), whose sum is σ = 20819215552. Its totient is φ = 20818617912.

The previous prime is 20818916717. The next prime is 20818916747. The reversal of 20818916731 is 13761981802.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20818916731 is a prime.

It is a super-2 number, since 2×20818916731² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20818916761) 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, 16525 + ... + 204721.

It is an arithmetic number, because the mean of its divisors is an integer number (5204803888).

Almost surely, 2^20818916731 is an apocalyptic number.

20818916731 is a deficient number, since it is larger than the sum of its proper divisors (298821).

20818916731 is a wasteful number, since it uses less digits than its factorization.

20818916731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298820.

The product of its (nonzero) digits is 145152, while the sum is 46.

The spelling of 20818916731 in words is "twenty billion, eight hundred eighteen million, nine hundred sixteen thousand, seven hundred thirty-one".