16661431 has 2 divisors, whose sum is σ = 16661432. Its totient is φ = 16661430.

The previous prime is 16661429. The next prime is 16661443. The reversal of 16661431 is 13416661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 16661431 - 2¹ = 16661429 is a prime.

It is a super-2 number, since 2×16661431² = 555206565935522, which contains 22 as substring.

Together with 16661429, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 16661431.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16661401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8330715 + 8330716.

It is an arithmetic number, because the mean of its divisors is an integer number (8330716).

Almost surely, 2^16661431 is an apocalyptic number.

16661431 is a deficient number, since it is larger than the sum of its proper divisors (1).

16661431 is an equidigital number, since it uses as much as digits as its factorization.

16661431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 28.

The square root of 16661431 is about 4081.8416186815. The cubic root of 16661431 is about 255.4097270582.

The spelling of 16661431 in words is "sixteen million, six hundred sixty-one thousand, four hundred thirty-one".