16133661 has 10 divisors (see below), whose sum is σ = 24101022. Its totient is φ = 10755720.

The previous prime is 16133647. The next prime is 16133681. The reversal of 16133661 is 16633161.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 16040025 + 93636 = 4005^2 + 306^2 .

It is not a de Polignac number, because 16133661 - 2⁶ = 16133597 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16133681) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 99510 + ... + 99671.

Almost surely, 2^16133661 is an apocalyptic number.

It is an amenable number.

16133661 is a deficient number, since it is larger than the sum of its proper divisors (7967361).

16133661 is an equidigital number, since it uses as much as digits as its factorization.

16133661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199193 (or 199184 counting only the distinct ones).

The product of its digits is 1944, while the sum is 27.

The square root of 16133661 is about 4016.6728768970. The cubic root of 16133661 is about 252.6839413871.

Subtracting 16133661 from its reverse (16633161), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 16133661 in words is "sixteen million, one hundred thirty-three thousand, six hundred sixty-one".