21243377 has 4 divisors (see below), whose sum is σ = 21386100. Its totient is φ = 21100656.

The previous prime is 21243361. The next prime is 21243403. The reversal of 21243377 is 77334212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4343056 + 16900321 = 2084^2 + 4111^2 .

It is a cyclic number.

It is not a de Polignac number, because 21243377 - 2⁴ = 21243361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21243307) 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 in 3 ways as a sum of consecutive naturals, for example, 71138 + ... + 71435.

It is an arithmetic number, because the mean of its divisors is an integer number (5346525).

Almost surely, 2^21243377 is an apocalyptic number.

It is an amenable number.

21243377 is a deficient number, since it is larger than the sum of its proper divisors (142723).

21243377 is a wasteful number, since it uses less digits than its factorization.

21243377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142722.

The product of its digits is 7056, while the sum is 29.

The square root of 21243377 is about 4609.0538074533. The cubic root of 21243377 is about 276.9541340386.

Adding to 21243377 its reverse (77334212), we get a palindrome (98577589).

The spelling of 21243377 in words is "twenty-one million, two hundred forty-three thousand, three hundred seventy-seven".