21673555 has 24 divisors (see below), whose sum is σ = 28248912. Its totient is φ = 15954432.

The previous prime is 21673523. The next prime is 21673559. The reversal of 21673555 is 55537612.

It is not a de Polignac number, because 21673555 - 2⁵ = 21673523 is a prime.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

Its product of digits (31500) is a multiple of the sum of its prime factors (375).

It is a self number, because there is not a number n which added to its sum of digits gives 21673555.

It is not an unprimeable number, because it can be changed into a prime (21673559) 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 23 ways as a sum of consecutive naturals, for example, 76444 + ... + 76726.

It is an arithmetic number, because the mean of its divisors is an integer number (1177038).

Almost surely, 2^21673555 is an apocalyptic number.

21673555 is a deficient number, since it is larger than the sum of its proper divisors (6575357).

21673555 is a wasteful number, since it uses less digits than its factorization.

21673555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 358 counting only the distinct ones).

The product of its digits is 31500, while the sum is 34.

The square root of 21673555 is about 4655.4865481494. The cubic root of 21673555 is about 278.8110941451.

The spelling of 21673555 in words is "twenty-one million, six hundred seventy-three thousand, five hundred fifty-five".