21751065 has 32 divisors (see below), whose sum is σ = 44194560. Its totient is φ = 9942912.

The previous prime is 21751043. The next prime is 21751069. The reversal of 21751065 is 56015712.

It is not a de Polignac number, because 21751065 - 2¹⁴ = 21734681 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21751069) 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 in 31 ways as a sum of consecutive naturals, for example, 10564 + ... + 12453.

It is an arithmetic number, because the mean of its divisors is an integer number (1381080).

Almost surely, 2^21751065 is an apocalyptic number.

It is an amenable number.

21751065 is an abundant number, since it is smaller than the sum of its proper divisors (22443495).

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

21751065 is a wasteful number, since it uses less digits than its factorization.

21751065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23038 (or 23032 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 21751065 is about 4663.8037051317. The cubic root of 21751065 is about 279.1430645624.

Adding to 21751065 its reverse (56015712), we get a palindrome (77766777).

It can be divided in two parts, 2175 and 1065, that added together give a triangular number (3240 = T₈₀).

The spelling of 21751065 in words is "twenty-one million, seven hundred fifty-one thousand, sixty-five".