21761272 has 32 divisors (see below), whose sum is σ = 44488080. Its totient is φ = 9918720.

The previous prime is 21761249. The next prime is 21761279. The reversal of 21761272 is 27216712.

It is a self number, because there is not a number n which added to its sum of digits gives 21761272.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21761279) 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 7 ways as a sum of consecutive naturals, for example, 7372 + ... + 9892.

Almost surely, 2^21761272 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21761272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22244040).

21761272 is an abundant number, since it is smaller than the sum of its proper divisors (22726808).

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

21761272 is a wasteful number, since it uses less digits than its factorization.

21761272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2623 (or 2619 counting only the distinct ones).

The product of its digits is 2352, while the sum is 28.

The square root of 21761272 is about 4664.8978552590. The cubic root of 21761272 is about 279.1867216997.

Adding to 21761272 its reverse (27216712), we get a palindrome (48977984).

The spelling of 21761272 in words is "twenty-one million, seven hundred sixty-one thousand, two hundred seventy-two".