21654818 has 4 divisors (see below), whose sum is σ = 32482230. Its totient is φ = 10827408.

The previous prime is 21654811. The next prime is 21654839. The reversal of 21654818 is 81845612.

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., 13741849 + 7912969 = 3707^2 + 2813^2 .

It is a super-2 number, since 2×21654818² = 937862285226248, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21654811) 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, 5413703 + ... + 5413706.

Almost surely, 2^21654818 is an apocalyptic number.

21654818 is a deficient number, since it is larger than the sum of its proper divisors (10827412).

21654818 is a wasteful number, since it uses less digits than its factorization.

21654818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10827411.

The product of its digits is 15360, while the sum is 35.

The square root of 21654818 is about 4653.4737562385. The cubic root of 21654818 is about 278.7307260095.

The spelling of 21654818 in words is "twenty-one million, six hundred fifty-four thousand, eight hundred eighteen".