16251981 has 8 divisors (see below), whose sum is σ = 21930720. Its totient is φ = 10703952.

The previous prime is 16251953. The next prime is 16251997. The reversal of 16251981 is 18915261.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16251981 - 2¹⁰ = 16250957 is a prime.

It is a super-2 number, since 2×16251981² = 528253772848722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16251941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32386 + ... + 32883.

It is an arithmetic number, because the mean of its divisors is an integer number (2741340).

Almost surely, 2^16251981 is an apocalyptic number.

It is an amenable number.

16251981 is a deficient number, since it is larger than the sum of its proper divisors (5678739).

16251981 is an equidigital number, since it uses as much as digits as its factorization.

16251981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65355.

The product of its digits is 4320, while the sum is 33.

The square root of 16251981 is about 4031.3745794704. The cubic root of 16251981 is about 253.3001431972.

The spelling of 16251981 in words is "sixteen million, two hundred fifty-one thousand, nine hundred eighty-one".