21903381681 has 16 divisors (see below), whose sum is σ = 29384417280. Its totient is φ = 14512441680.

The previous prime is 21903381671. The next prime is 21903381683. The reversal of 21903381681 is 18618330912.

It is not a de Polignac number, because 21903381681 - 2⁵ = 21903381649 is a prime.

It is a super-2 number, since 2×21903381681² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21903381683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 626460 + ... + 660498.

It is an arithmetic number, because the mean of its divisors is an integer number (1836526080).

Almost surely, 2^21903381681 is an apocalyptic number.

It is an amenable number.

21903381681 is a deficient number, since it is larger than the sum of its proper divisors (7481035599).

21903381681 is a wasteful number, since it uses less digits than its factorization.

21903381681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35356.

The product of its (nonzero) digits is 62208, while the sum is 42.

The spelling of 21903381681 in words is "twenty-one billion, nine hundred three million, three hundred eighty-one thousand, six hundred eighty-one".