16661437 has 4 divisors (see below), whose sum is σ = 17943100. Its totient is φ = 15379776.

The previous prime is 16661431. The next prime is 16661443. The reversal of 16661437 is 73416661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 73416661 = 29 ⋅2531609.

It is an interprime number because it is at equal distance from previous prime (16661431) and next prime (16661443).

It can be written as a sum of positive squares in 2 ways, for example, as 11329956 + 5331481 = 3366^2 + 2309^2 .

It is a cyclic number.

It is not a de Polignac number, because 16661437 - 2³ = 16661429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16661431) 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, 640812 + ... + 640837.

It is an arithmetic number, because the mean of its divisors is an integer number (4485775).

Almost surely, 2^16661437 is an apocalyptic number.

It is an amenable number.

16661437 is a deficient number, since it is larger than the sum of its proper divisors (1281663).

16661437 is a wasteful number, since it uses less digits than its factorization.

16661437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1281662.

The product of its digits is 18144, while the sum is 34.

The square root of 16661437 is about 4081.8423536438. The cubic root of 16661437 is about 255.4097577170.

The spelling of 16661437 in words is "sixteen million, six hundred sixty-one thousand, four hundred thirty-seven".