16517621 has 2 divisors, whose sum is σ = 16517622. Its totient is φ = 16517620.

The previous prime is 16517551. The next prime is 16517623. The reversal of 16517621 is 12671561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15689521 + 828100 = 3961^2 + 910^2 .

It is a cyclic number.

It is not a de Polignac number, because 16517621 - 2¹⁰ = 16516597 is a prime.

Together with 16517623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16517623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8258810 + 8258811.

It is an arithmetic number, because the mean of its divisors is an integer number (8258811).

Almost surely, 2^16517621 is an apocalyptic number.

It is an amenable number.

16517621 is a deficient number, since it is larger than the sum of its proper divisors (1).

16517621 is an equidigital number, since it uses as much as digits as its factorization.

16517621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2520, while the sum is 29.

The square root of 16517621 is about 4064.1876187007. The cubic root of 16517621 is about 254.6727623499.

The spelling of 16517621 in words is "sixteen million, five hundred seventeen thousand, six hundred twenty-one".