21641368 has 32 divisors (see below), whose sum is σ = 47036160. Its totient is φ = 9142560.

The previous prime is 21641359. The next prime is 21641369. The reversal of 21641368 is 86314612.

It is a happy number.

It is a super-2 number, since 2×21641368² = 936697617822848, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21641369) 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, 1255 + ... + 6697.

It is an arithmetic number, because the mean of its divisors is an integer number (1469880).

Almost surely, 2^21641368 is an apocalyptic number.

21641368 is a gapful number since it is divisible by the number (28) 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 21641368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23518080).

21641368 is an abundant number, since it is smaller than the sum of its proper divisors (25394792).

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

21641368 is a wasteful number, since it uses less digits than its factorization.

21641368 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5527 (or 5523 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21641368 is about 4652.0283748060. The cubic root of 21641368 is about 278.6730066805.

The spelling of 21641368 in words is "twenty-one million, six hundred forty-one thousand, three hundred sixty-eight".