16211621 has 8 divisors (see below), whose sum is σ = 16563864. Its totient is φ = 15863040.

The previous prime is 16211599. The next prime is 16211623. The reversal of 16211621 is 12611261.

It can be written as a sum of positive squares in 4 ways, for example, as 5354596 + 10857025 = 2314^2 + 3295^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16211621 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16211593 and 16211602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16211623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9191 + ... + 10811.

It is an arithmetic number, because the mean of its divisors is an integer number (2070483).

Almost surely, 2^16211621 is an apocalyptic number.

It is an amenable number.

16211621 is a deficient number, since it is larger than the sum of its proper divisors (352243).

16211621 is a wasteful number, since it uses less digits than its factorization.

16211621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1831.

The product of its digits is 144, while the sum is 20.

The square root of 16211621 is about 4026.3657310284. The cubic root of 16211621 is about 253.0902884068.

Adding to 16211621 its reverse (12611261), we get a palindrome (28822882).

The spelling of 16211621 in words is "sixteen million, two hundred eleven thousand, six hundred twenty-one".