16163321781 has 4 divisors (see below), whose sum is σ = 21551095712. Its totient is φ = 10775547852.

The previous prime is 16163321777. The next prime is 16163321819. The reversal of 16163321781 is 18712336161.

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 not a de Polignac number, because 16163321781 - 2² = 16163321777 is a prime.

It is a super-2 number, since 2×16163321781² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16163321701) 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, 2693886961 + ... + 2693886966.

It is an arithmetic number, because the mean of its divisors is an integer number (5387773928).

Almost surely, 2^16163321781 is an apocalyptic number.

It is an amenable number.

16163321781 is a deficient number, since it is larger than the sum of its proper divisors (5387773931).

16163321781 is an equidigital number, since it uses as much as digits as its factorization.

16163321781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5387773930.

The product of its digits is 36288, while the sum is 39.

The spelling of 16163321781 in words is "sixteen billion, one hundred sixty-three million, three hundred twenty-one thousand, seven hundred eighty-one".