21835381 has 4 divisors (see below), whose sum is σ = 21854764. Its totient is φ = 21816000.

The previous prime is 21835343. The next prime is 21835393. The reversal of 21835381 is 18353812.

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 8940100 + 12895281 = 2990^2 + 3591^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21835381 is a prime.

It is a super-2 number, since 2×21835381² = 953567726830322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21835321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7890 + ... + 10291.

It is an arithmetic number, because the mean of its divisors is an integer number (5463691).

Almost surely, 2^21835381 is an apocalyptic number.

It is an amenable number.

21835381 is a deficient number, since it is larger than the sum of its proper divisors (19383).

21835381 is a wasteful number, since it uses less digits than its factorization.

21835381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19382.

The product of its digits is 5760, while the sum is 31.

The square root of 21835381 is about 4672.8343647084. The cubic root of 21835381 is about 279.5032902947.

The spelling of 21835381 in words is "twenty-one million, eight hundred thirty-five thousand, three hundred eighty-one".