21617272 has 8 divisors (see below), whose sum is σ = 40532400. Its totient is φ = 10808632.

The previous prime is 21617249. The next prime is 21617273. The reversal of 21617272 is 27271612.

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21617272.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21617273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1351072 + ... + 1351087.

It is an arithmetic number, because the mean of its divisors is an integer number (5066550).

Almost surely, 2^21617272 is an apocalyptic number.

It is an amenable number.

21617272 is a deficient number, since it is larger than the sum of its proper divisors (18915128).

21617272 is a wasteful number, since it uses less digits than its factorization.

21617272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2702165 (or 2702161 counting only the distinct ones).

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

The square root of 21617272 is about 4649.4378154783. The cubic root of 21617272 is about 278.5695412790.

Adding to 21617272 its reverse (27271612), we get a palindrome (48888884).

The spelling of 21617272 in words is "twenty-one million, six hundred seventeen thousand, two hundred seventy-two".