21243777 has 8 divisors (see below), whose sum is σ = 28397280. Its totient is φ = 14126400.

The previous prime is 21243769. The next prime is 21243779. The reversal of 21243777 is 77734212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21243777 - 2³ = 21243769 is a prime.

It is a super-2 number, since 2×21243777² = 902596122451458, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21243779) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7627 + ... + 10032.

It is an arithmetic number, because the mean of its divisors is an integer number (3549660).

Almost surely, 2^21243777 is an apocalyptic number.

It is an amenable number.

21243777 is a deficient number, since it is larger than the sum of its proper divisors (7153503).

21243777 is a wasteful number, since it uses less digits than its factorization.

21243777 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18063.

The product of its digits is 16464, while the sum is 33.

The square root of 21243777 is about 4609.0972001033. The cubic root of 21243777 is about 276.9558723208.

Adding to 21243777 its reverse (77734212), we get a palindrome (98977989).

The spelling of 21243777 in words is "twenty-one million, two hundred forty-three thousand, seven hundred seventy-seven".