21023738 has 4 divisors (see below), whose sum is σ = 31535610. Its totient is φ = 10511868.

The previous prime is 21023731. The next prime is 21023741. The reversal of 21023738 is 83732012.

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

It can be written as a sum of positive squares in only one way, i.e., 11580409 + 9443329 = 3403^2 + 3073^2 .

It is not an unprimeable number, because it can be changed into a prime (21023731) 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 as a sum of consecutive naturals, namely, 5255933 + ... + 5255936.

Almost surely, 2^21023738 is an apocalyptic number.

21023738 is a deficient number, since it is larger than the sum of its proper divisors (10511872).

21023738 is a wasteful number, since it uses less digits than its factorization.

21023738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10511871.

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 21023738 is about 4585.1649915788. The cubic root of 21023738 is about 275.9963330046.

The spelling of 21023738 in words is "twenty-one million, twenty-three thousand, seven hundred thirty-eight".