21916458 has 24 divisors (see below), whose sum is σ = 47639748. Its totient is φ = 7281792.

The previous prime is 21916439. The next prime is 21916459. The reversal of 21916458 is 85461912.

21916458 is a `hidden beast` number, since 2 + 1 + 9 + 1 + 645 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16867449 + 5049009 = 4107^2 + 2247^2 .

It is a super-2 number, since 2×21916458² = 960662262531528, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21916459) 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 11 ways as a sum of consecutive naturals, for example, 4260 + ... + 7872.

Almost surely, 2^21916458 is an apocalyptic number.

21916458 is an abundant number, since it is smaller than the sum of its proper divisors (25723290).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21916458 is a wasteful number, since it uses less digits than its factorization.

21916458 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3958 (or 3955 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 21916458 is about 4681.5016821529. The cubic root of 21916458 is about 279.8488044259.

It can be divided in two parts, 2191 and 6458, that added together give a square (8649 = 93²).

The spelling of 21916458 in words is "twenty-one million, nine hundred sixteen thousand, four hundred fifty-eight".