21140064 has 72 divisors (see below), whose sum is σ = 65592072. Its totient is φ = 6405120.

The previous prime is 21140033. The next prime is 21140069. The reversal of 21140064 is 46004112.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140069) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 169 + ... + 6504.

It is an arithmetic number, because the mean of its divisors is an integer number (911001).

Almost surely, 2^21140064 is an apocalyptic number.

21140064 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 21140064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32796036).

21140064 is an abundant number, since it is smaller than the sum of its proper divisors (44452008).

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

21140064 is a wasteful number, since it uses less digits than its factorization.

21140064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6700 (or 6689 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21140064 is about 4597.8325328354. The cubic root of 21140064 is about 276.5044335242.

Adding to 21140064 its reverse (46004112), we get a palindrome (67144176).

The spelling of 21140064 in words is "twenty-one million, one hundred forty thousand, sixty-four".