21282751 has 16 divisors (see below), whose sum is σ = 25772544. Its totient is φ = 17180064.

The previous prime is 21282743. The next prime is 21282761. The reversal of 21282751 is 15728212.

It is a cyclic number.

It is not a de Polignac number, because 21282751 - 2³ = 21282743 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21282761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9801 + ... + 11773.

It is an arithmetic number, because the mean of its divisors is an integer number (1610784).

Almost surely, 2^21282751 is an apocalyptic number.

21282751 is a deficient number, since it is larger than the sum of its proper divisors (4489793).

21282751 is a wasteful number, since it uses less digits than its factorization.

21282751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070.

The product of its digits is 2240, while the sum is 28.

The square root of 21282751 is about 4613.3232056729. The cubic root of 21282751 is about 277.1251373237.

It can be divided in two parts, 212827 and 51, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 21282751 in words is "twenty-one million, two hundred eighty-two thousand, seven hundred fifty-one".