21742816 has 12 divisors (see below), whose sum is σ = 42806232. Its totient is φ = 10871392.

The previous prime is 21742793. The next prime is 21742817. The reversal of 21742816 is 61824712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339700 + ... + 339763.

It is an arithmetic number, because the mean of its divisors is an integer number (3567186).

Almost surely, 2^21742816 is an apocalyptic number.

It is an amenable number.

21742816 is a deficient number, since it is larger than the sum of its proper divisors (21063416).

21742816 is an equidigital number, since it uses as much as digits as its factorization.

21742816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 679473 (or 679465 counting only the distinct ones).

The product of its digits is 5376, while the sum is 31.

The square root of 21742816 is about 4662.9192572894. The cubic root of 21742816 is about 279.1077721558.

The spelling of 21742816 in words is "twenty-one million, seven hundred forty-two thousand, eight hundred sixteen".