21065388 has 24 divisors (see below), whose sum is σ = 49334208. Its totient is φ = 6995856.

The previous prime is 21065381. The next prime is 21065413. The reversal of 21065388 is 88356012.

It is a happy number.

It is a super-3 number, since 3×21065388³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21065381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 295 + ... + 6497.

It is an arithmetic number, because the mean of its divisors is an integer number (2055592).

Almost surely, 2^21065388 is an apocalyptic number.

It is an amenable number.

21065388 is an abundant number, since it is smaller than the sum of its proper divisors (28268820).

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

21065388 is a wasteful number, since it uses less digits than its factorization.

21065388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6493 (or 6491 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21065388 is about 4589.7045656556. The cubic root of 21065388 is about 276.1784710011.

The spelling of 21065388 in words is "twenty-one million, sixty-five thousand, three hundred eighty-eight".