21641200381 has 4 divisors (see below), whose sum is σ = 22387448700. Its totient is φ = 20894952064.

The previous prime is 21641200367. The next prime is 21641200429. The reversal of 21641200381 is 18300214612.

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 14191956900 + 7449243481 = 119130^2 + 86309^2 .

It is a cyclic number.

It is not a de Polignac number, because 21641200381 - 2¹³ = 21641192189 is a prime.

It is a super-2 number, since 2×21641200381² (a number of 21 digits) 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 (21641200331) 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, 373124116 + ... + 373124173.

It is an arithmetic number, because the mean of its divisors is an integer number (5596862175).

Almost surely, 2^21641200381 is an apocalyptic number.

It is an amenable number.

21641200381 is a deficient number, since it is larger than the sum of its proper divisors (746248319).

21641200381 is an equidigital number, since it uses as much as digits as its factorization.

21641200381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 746248318.

The product of its (nonzero) digits is 2304, while the sum is 28.

Adding to 21641200381 its reverse (18300214612), we get a palindrome (39941414993).

The spelling of 21641200381 in words is "twenty-one billion, six hundred forty-one million, two hundred thousand, three hundred eighty-one".