21667481 has 8 divisors (see below), whose sum is σ = 24400128. Its totient is φ = 19062000.

The previous prime is 21667463. The next prime is 21667489. The reversal of 21667481 is 18476612.

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

It is a cyclic number.

It is not a de Polignac number, because 21667481 - 2⁶ = 21667417 is a prime.

It is a super-2 number, since 2×21667481² = 938959465770722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21667489) 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 7 ways as a sum of consecutive naturals, for example, 31430 + ... + 32111.

It is an arithmetic number, because the mean of its divisors is an integer number (3050016).

Almost surely, 2^21667481 is an apocalyptic number.

It is an amenable number.

21667481 is a deficient number, since it is larger than the sum of its proper divisors (2732647).

21667481 is a wasteful number, since it uses less digits than its factorization.

21667481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63583.

The product of its digits is 16128, while the sum is 35.

The square root of 21667481 is about 4654.8341538663. The cubic root of 21667481 is about 278.7850461677.

The spelling of 21667481 in words is "twenty-one million, six hundred sixty-seven thousand, four hundred eighty-one".