21266064 has 100 divisors (see below), whose sum is σ = 62791740. Its totient is φ = 6946560.

The previous prime is 21266059. The next prime is 21266071. The reversal of 21266064 is 46066212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1016064 + 20250000 = 1008^2 + 4500^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 11.

It is a congruent number.

It is an unprimeable number.

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 in 19 ways as a sum of consecutive naturals, for example, 78922 + ... + 79190.

Almost surely, 2^21266064 is an apocalyptic number.

21266064 is a gapful number since it is divisible by the number (24) 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 21266064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31395870).

21266064 is an abundant number, since it is smaller than the sum of its proper divisors (41525676).

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

21266064 is a wasteful number, since it uses less digits than its factorization.

21266064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350 (or 335 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21266064 is about 4611.5142849177. The cubic root of 21266064 is about 277.0526906070.

It can be divided in two parts, 21 and 266064, that added together give a triangular number (266085 = T₇₂₉).

The spelling of 21266064 in words is "twenty-one million, two hundred sixty-six thousand, sixty-four".