21801238 has 4 divisors (see below), whose sum is σ = 32701860. Its totient is φ = 10900618.

The previous prime is 21801211. The next prime is 21801271. The reversal of 21801238 is 83210812.

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

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, 5450308 + ... + 5450311.

It is an arithmetic number, because the mean of its divisors is an integer number (8175465).

Almost surely, 2^21801238 is an apocalyptic number.

21801238 is a deficient number, since it is larger than the sum of its proper divisors (10900622).

21801238 is a wasteful number, since it uses less digits than its factorization.

21801238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10900621.

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21801238 is about 4669.1795853233. The cubic root of 21801238 is about 279.3575320687.

The spelling of 21801238 in words is "twenty-one million, eight hundred one thousand, two hundred thirty-eight".