21545272 has 16 divisors (see below), whose sum is σ = 46168560. Its totient is φ = 9233664.

The previous prime is 21545263. The next prime is 21545309. The reversal of 21545272 is 27254512.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 21545272.

It is a congruent number.

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, 192313 + ... + 192424.

It is an arithmetic number, because the mean of its divisors is an integer number (2885535).

Almost surely, 2^21545272 is an apocalyptic number.

It is an amenable number.

21545272 is an abundant number, since it is smaller than the sum of its proper divisors (24623288).

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

21545272 is a wasteful number, since it uses less digits than its factorization.

21545272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384750 (or 384746 counting only the distinct ones).

The product of its digits is 5600, while the sum is 28.

The square root of 21545272 is about 4641.6884858853. The cubic root of 21545272 is about 278.2599228710.

Adding to 21545272 its reverse (27254512), we get a palindrome (48799784).

The spelling of 21545272 in words is "twenty-one million, five hundred forty-five thousand, two hundred seventy-two".