21481738 has 4 divisors (see below), whose sum is σ = 32222610. Its totient is φ = 10740868.

The previous prime is 21481709. The next prime is 21481739. The reversal of 21481738 is 83718412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19210689 + 2271049 = 4383^2 + 1507^2 .

It is a super-2 number, since 2×21481738² = 922930135001288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21481739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5370433 + ... + 5370436.

Almost surely, 2^21481738 is an apocalyptic number.

21481738 is a deficient number, since it is larger than the sum of its proper divisors (10740872).

21481738 is a wasteful number, since it uses less digits than its factorization.

21481738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10740871.

The product of its digits is 10752, while the sum is 34.

The square root of 21481738 is about 4634.8395872997. The cubic root of 21481738 is about 277.9861370172.

The spelling of 21481738 in words is "twenty-one million, four hundred eighty-one thousand, seven hundred thirty-eight".