16123981 has 4 divisors (see below), whose sum is σ = 16170012. Its totient is φ = 16077952.

The previous prime is 16123969. The next prime is 16123993. The reversal of 16123981 is 18932161.

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

It is an interprime number because it is at equal distance from previous prime (16123969) and next prime (16123993).

It can be written as a sum of positive squares in 2 ways, for example, as 10989225 + 5134756 = 3315^2 + 2266^2 .

It is a cyclic number.

It is not a de Polignac number, because 16123981 - 2⁷ = 16123853 is a prime.

It is a super-2 number, since 2×16123981² = 519965526576722, which 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 (16123901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22486 + ... + 23191.

It is an arithmetic number, because the mean of its divisors is an integer number (4042503).

Almost surely, 2^16123981 is an apocalyptic number.

It is an amenable number.

16123981 is a deficient number, since it is larger than the sum of its proper divisors (46031).

16123981 is an equidigital number, since it uses as much as digits as its factorization.

16123981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46030.

The product of its digits is 2592, while the sum is 31.

The square root of 16123981 is about 4015.4677187097. The cubic root of 16123981 is about 252.6333955149.

It can be divided in two parts, 161 and 23981, that added together give a palindrome (24142).

The spelling of 16123981 in words is "sixteen million, one hundred twenty-three thousand, nine hundred eighty-one".