16381644 has 12 divisors (see below), whose sum is σ = 38223864. Its totient is φ = 5460544.

The previous prime is 16381633. The next prime is 16381649. The reversal of 16381644 is 44618361.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (16381649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 682557 + ... + 682580.

It is an arithmetic number, because the mean of its divisors is an integer number (3185322).

Almost surely, 2^16381644 is an apocalyptic number.

It is an amenable number.

16381644 is an abundant number, since it is smaller than the sum of its proper divisors (21842220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16381644 is a wasteful number, since it uses less digits than its factorization.

16381644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1365144 (or 1365142 counting only the distinct ones).

The product of its digits is 13824, while the sum is 33.

The square root of 16381644 is about 4047.4243661865. The cubic root of 16381644 is about 253.9719935227.

The spelling of 16381644 in words is "sixteen million, three hundred eighty-one thousand, six hundred forty-four".