21224727 has 16 divisors (see below), whose sum is σ = 31591680. Its totient is φ = 14083416.

The previous prime is 21224689. The next prime is 21224737. The reversal of 21224727 is 72742212.

It is not a de Polignac number, because 21224727 - 2¹¹ = 21222679 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21224727.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224737) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4398 + ... + 7860.

It is an arithmetic number, because the mean of its divisors is an integer number (1974480).

Almost surely, 2^21224727 is an apocalyptic number.

21224727 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21224727 is a deficient number, since it is larger than the sum of its proper divisors (10366953).

21224727 is a wasteful number, since it uses less digits than its factorization.

21224727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3699 (or 3693 counting only the distinct ones).

The product of its digits is 3136, while the sum is 27.

The square root of 21224727 is about 4607.0301713794. The cubic root of 21224727 is about 276.8730623885.

Adding to 21224727 its reverse (72742212), we get a palindrome (93966939).

The spelling of 21224727 in words is "twenty-one million, two hundred twenty-four thousand, seven hundred twenty-seven".