16081821 has 40 divisors (see below), whose sum is σ = 27808704. Its totient is φ = 9072000.

The previous prime is 16081817. The next prime is 16081823. The reversal of 16081821 is 12818061.

It is not a de Polignac number, because 16081821 - 2² = 16081817 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16081823) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 63946 + ... + 64196.

Almost surely, 2^16081821 is an apocalyptic number.

It is an amenable number.

16081821 is a deficient number, since it is larger than the sum of its proper divisors (11726883).

16081821 is a wasteful number, since it uses less digits than its factorization.

16081821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383 (or 374 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 16081821 is about 4010.2145827873. The cubic root of 16081821 is about 252.4130132020.

Adding to 16081821 its reverse (12818061), we get a palindrome (28899882).

The spelling of 16081821 in words is "sixteen million, eighty-one thousand, eight hundred twenty-one".