21005272 has 16 divisors (see below), whose sum is σ = 39481200. Its totient is φ = 10476960.

The previous prime is 21005269. The next prime is 21005291. The reversal of 21005272 is 27250012.

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, 522 + ... + 6502.

It is an arithmetic number, because the mean of its divisors is an integer number (2467575).

Almost surely, 2^21005272 is an apocalyptic number.

It is an amenable number.

21005272 is a deficient number, since it is larger than the sum of its proper divisors (18475928).

21005272 is a wasteful number, since it uses less digits than its factorization.

21005272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6426 (or 6422 counting only the distinct ones).

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 21005272 is about 4583.1508812170. The cubic root of 21005272 is about 275.9155030846.

Adding to 21005272 its reverse (27250012), we get a palindrome (48255284).

The spelling of 21005272 in words is "twenty-one million, five thousand, two hundred seventy-two".