21505352 has 16 divisors (see below), whose sum is σ = 43988400. Its totient is φ = 9775120.

The previous prime is 21505349. The next prime is 21505381. The reversal of 21505352 is 25350512.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122102 + ... + 122277.

It is an arithmetic number, because the mean of its divisors is an integer number (2749275).

Almost surely, 2^21505352 is an apocalyptic number.

21505352 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21505352 is an abundant number, since it is smaller than the sum of its proper divisors (22483048).

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

21505352 is a wasteful number, since it uses less digits than its factorization.

21505352 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244396 (or 244392 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 23.

The square root of 21505352 is about 4637.3863328388. The cubic root of 21505352 is about 278.0879593309.

Adding to 21505352 its reverse (25350512), we get a palindrome (46855864).

The spelling of 21505352 in words is "twenty-one million, five hundred five thousand, three hundred fifty-two".