21245772 has 12 divisors (see below), whose sum is σ = 49573496. Its totient is φ = 7081920.

The previous prime is 21245771. The next prime is 21245773. The reversal of 21245772 is 27754212.

It is an interprime number because it is at equal distance from previous prime (21245771) and next prime (21245773).

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 885229 + ... + 885252.

Almost surely, 2^21245772 is an apocalyptic number.

It is an amenable number.

21245772 is an abundant number, since it is smaller than the sum of its proper divisors (28327724).

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

21245772 is a wasteful number, since it uses less digits than its factorization.

21245772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1770488 (or 1770486 counting only the distinct ones).

The product of its digits is 7840, while the sum is 30.

The square root of 21245772 is about 4609.3136148455. The cubic root of 21245772 is about 276.9645416780.

Adding to 21245772 its reverse (27754212), we get a palindrome (48999984).

The spelling of 21245772 in words is "twenty-one million, two hundred forty-five thousand, seven hundred seventy-two".