21738081 has 8 divisors (see below), whose sum is σ = 29983680. Its totient is φ = 13992272.

The previous prime is 21738049. The next prime is 21738089. The reversal of 21738081 is 18083712.

It is a happy number.

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 21738081 - 2⁵ = 21738049 is a prime.

It is a super-2 number, since 2×21738081² = 945088331125122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21738089) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124845 + ... + 125018.

It is an arithmetic number, because the mean of its divisors is an integer number (3747960).

Almost surely, 2^21738081 is an apocalyptic number.

It is an amenable number.

21738081 is a deficient number, since it is larger than the sum of its proper divisors (8245599).

21738081 is a wasteful number, since it uses less digits than its factorization.

21738081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249895.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 21738081 is about 4662.4115005006. The cubic root of 21738081 is about 279.0875099651.

The spelling of 21738081 in words is "twenty-one million, seven hundred thirty-eight thousand, eighty-one".