21642064 has 20 divisors (see below), whose sum is σ = 44139040. Its totient is φ = 10251360.

The previous prime is 21642017. The next prime is 21642067. The reversal of 21642064 is 46024612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642067) 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 in 3 ways as a sum of consecutive naturals, for example, 35292 + ... + 35899.

It is an arithmetic number, because the mean of its divisors is an integer number (2206952).

Almost surely, 2^21642064 is an apocalyptic number.

It is an amenable number.

21642064 is an abundant number, since it is smaller than the sum of its proper divisors (22496976).

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

21642064 is a wasteful number, since it uses less digits than its factorization.

21642064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71218 (or 71212 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 21642064 is about 4652.1031802831. The cubic root of 21642064 is about 278.6759940815.

Adding to 21642064 its reverse (46024612), we get a palindrome (67666676).

The spelling of 21642064 in words is "twenty-one million, six hundred forty-two thousand, sixty-four".