16690981 has 4 divisors (see below), whose sum is σ = 16811200. Its totient is φ = 16570764.

The previous prime is 16690963. The next prime is 16690997. The reversal of 16690981 is 18909661.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18909661 = 17 ⋅1112333.

It is a cyclic number.

It is not a de Polignac number, because 16690981 - 2⁹ = 16690469 is a prime.

It is a super-2 number, since 2×16690981² = 557177693484722, 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 (16690381) 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, 59901 + ... + 60178.

It is an arithmetic number, because the mean of its divisors is an integer number (4202800).

Almost surely, 2^16690981 is an apocalyptic number.

It is an amenable number.

16690981 is a deficient number, since it is larger than the sum of its proper divisors (120219).

16690981 is a wasteful number, since it uses less digits than its factorization.

16690981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120218.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 16690981 is about 4085.4597048557. The cubic root of 16690981 is about 255.5606324623.

It can be divided in two parts, 16690 and 981, that added together give a palindrome (17671).

The spelling of 16690981 in words is "sixteen million, six hundred ninety thousand, nine hundred eighty-one".