21458736 has 80 divisors (see below), whose sum is σ = 66349920. Its totient is φ = 6600960.

The previous prime is 21458719. The next prime is 21458741. The reversal of 21458736 is 63785412.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21458736.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 3706 + ... + 7526.

It is an arithmetic number, because the mean of its divisors is an integer number (829374).

Almost surely, 2^21458736 is an apocalyptic number.

21458736 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21458736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33174960).

21458736 is an abundant number, since it is smaller than the sum of its proper divisors (44891184).

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

21458736 is a wasteful number, since it uses less digits than its factorization.

21458736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3851 (or 3839 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21458736 is about 4632.3574991574. The cubic root of 21458736 is about 277.8868818463.

The spelling of 21458736 in words is "twenty-one million, four hundred fifty-eight thousand, seven hundred thirty-six".