21023438 has 4 divisors (see below), whose sum is σ = 31535160. Its totient is φ = 10511718.

The previous prime is 21023419. The next prime is 21023459. The reversal of 21023438 is 83432012.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 5255858 + ... + 5255861.

It is an arithmetic number, because the mean of its divisors is an integer number (7883790).

Almost surely, 2^21023438 is an apocalyptic number.

21023438 is a deficient number, since it is larger than the sum of its proper divisors (10511722).

21023438 is a wasteful number, since it uses less digits than its factorization.

21023438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10511721.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 21023438 is about 4585.1322772631. The cubic root of 21023438 is about 275.9950202140.

The spelling of 21023438 in words is "twenty-one million, twenty-three thousand, four hundred thirty-eight".