21431767 has 12 divisors (see below), whose sum is σ = 25036680. Its totient is φ = 18292176.

The previous prime is 21431749. The next prime is 21431777. The reversal of 21431767 is 76713412.

It is not a de Polignac number, because 21431767 - 2¹¹ = 21429719 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 (21431717) 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, 12784 + ... + 14362.

It is an arithmetic number, because the mean of its divisors is an integer number (2086390).

Almost surely, 2^21431767 is an apocalyptic number.

21431767 is a deficient number, since it is larger than the sum of its proper divisors (3604913).

21431767 is a wasteful number, since it uses less digits than its factorization.

21431767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1870 (or 1863 counting only the distinct ones).

The product of its digits is 7056, while the sum is 31.

The square root of 21431767 is about 4629.4456471591. The cubic root of 21431767 is about 277.7704184302.

The spelling of 21431767 in words is "twenty-one million, four hundred thirty-one thousand, seven hundred sixty-seven".