16697781 has 12 divisors (see below), whose sum is σ = 24246508. Its totient is φ = 11073024.

The previous prime is 16697773. The next prime is 16697797. The reversal of 16697781 is 18779661.

It can be written as a sum of positive squares in 2 ways, for example, as 12006225 + 4691556 = 3465^2 + 2166^2 .

It is not a de Polignac number, because 16697781 - 2³ = 16697773 is a prime.

It is a super-2 number, since 2×16697781² = 557631780647922, 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 (16697711) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3070 + ... + 6543.

Almost surely, 2^16697781 is an apocalyptic number.

It is an amenable number.

16697781 is a deficient number, since it is larger than the sum of its proper divisors (7548727).

16697781 is a wasteful number, since it uses less digits than its factorization.

16697781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9812 (or 9809 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 16697781 is about 4086.2918397980. The cubic root of 16697781 is about 255.5953333657.

The spelling of 16697781 in words is "sixteen million, six hundred ninety-seven thousand, seven hundred eighty-one".