16221765 has 16 divisors (see below), whose sum is σ = 29662848. Its totient is φ = 7415616.

The previous prime is 16221761. The next prime is 16221823. The reversal of 16221765 is 56712261.

It is not a de Polignac number, because 16221765 - 2² = 16221761 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16221761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77142 + ... + 77351.

It is an arithmetic number, because the mean of its divisors is an integer number (1853928).

Almost surely, 2^16221765 is an apocalyptic number.

16221765 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

16221765 is a deficient number, since it is larger than the sum of its proper divisors (13441083).

16221765 is a wasteful number, since it uses less digits than its factorization.

16221765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154508.

The product of its digits is 5040, while the sum is 30.

The square root of 16221765 is about 4027.6252308277. The cubic root of 16221765 is about 253.1430656212.

The spelling of 16221765 in words is "sixteen million, two hundred twenty-one thousand, seven hundred sixty-five".