21243767 has 12 divisors (see below), whose sum is σ = 22722840. Its totient is φ = 19855152.

The previous prime is 21243731. The next prime is 21243769. The reversal of 21243767 is 76734212.

It is not a de Polignac number, because 21243767 - 2¹² = 21239671 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243769) 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 11 ways as a sum of consecutive naturals, for example, 29609 + ... + 30317.

It is an arithmetic number, because the mean of its divisors is an integer number (1893570).

Almost surely, 2^21243767 is an apocalyptic number.

21243767 is a deficient number, since it is larger than the sum of its proper divisors (1479073).

21243767 is an equidigital number, since it uses as much as digits as its factorization.

21243767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 830 (or 811 counting only the distinct ones).

The product of its digits is 14112, while the sum is 32.

The square root of 21243767 is about 4609.0961152920. The cubic root of 21243767 is about 276.9558288641.

Adding to 21243767 its reverse (76734212), we get a palindrome (97977979).

The spelling of 21243767 in words is "twenty-one million, two hundred forty-three thousand, seven hundred sixty-seven".