16213981 has 8 divisors (see below), whose sum is σ = 18598464. Its totient is φ = 13846560.

The previous prime is 16213979. The next prime is 16213991. The reversal of 16213981 is 18931261.

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

It is not a de Polignac number, because 16213981 - 2¹ = 16213979 is a prime.

It is a super-2 number, since 2×16213981² = 525786359736722, 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 (16213921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2155 + ... + 6088.

It is an arithmetic number, because the mean of its divisors is an integer number (2324808).

Almost surely, 2^16213981 is an apocalyptic number.

It is an amenable number.

16213981 is a deficient number, since it is larger than the sum of its proper divisors (2384483).

16213981 is an equidigital number, since it uses as much as digits as its factorization.

16213981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8531.

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

The square root of 16213981 is about 4026.6587886236. The cubic root of 16213981 is about 253.1025689822.

The spelling of 16213981 in words is "sixteen million, two hundred thirteen thousand, nine hundred eighty-one".