21269664 has 216 divisors, whose sum is σ = 71940960. Its totient is φ = 5930496.

The previous prime is 21269659. The next prime is 21269681. The reversal of 21269664 is 46696212.

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

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 924757 + ... + 924779.

It is an arithmetic number, because the mean of its divisors is an integer number (333060).

Almost surely, 2^21269664 is an apocalyptic number.

21269664 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 21269664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35970480).

21269664 is an abundant number, since it is smaller than the sum of its proper divisors (50671296).

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

21269664 is a wasteful number, since it uses less digits than its factorization.

21269664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 60 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 21269664 is about 4611.9045957175. The cubic root of 21269664 is about 277.0683232351.

The spelling of 21269664 in words is "twenty-one million, two hundred sixty-nine thousand, six hundred sixty-four".