16643531 has 2 divisors, whose sum is σ = 16643532. Its totient is φ = 16643530.

The previous prime is 16643521. The next prime is 16643533. The reversal of 16643531 is 13534661.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16643531 is a prime.

It is a super-2 number, since 2×16643531² = 554014248295922, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 16643533, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 16643494 and 16643503.

It is not a weakly prime, because it can be changed into another prime (16643533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8321765 + 8321766.

It is an arithmetic number, because the mean of its divisors is an integer number (8321766).

Almost surely, 2^16643531 is an apocalyptic number.

16643531 is a deficient number, since it is larger than the sum of its proper divisors (1).

16643531 is an equidigital number, since it uses as much as digits as its factorization.

16643531 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 29.

The square root of 16643531 is about 4079.6483917122. The cubic root of 16643531 is about 255.3182288685.

The spelling of 16643531 in words is "sixteen million, six hundred forty-three thousand, five hundred thirty-one".