21043843771 has 16 divisors (see below), whose sum is σ = 22547052864. Its totient is φ = 19570765824.

The previous prime is 21043843747. The next prime is 21043843817. The reversal of 21043843771 is 17734834012.

It is a cyclic number.

It is not a de Polignac number, because 21043843771 - 2²¹ = 21041746619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21043843571) 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, 1067026 + ... + 1086568.

It is an arithmetic number, because the mean of its divisors is an integer number (1409190804).

Almost surely, 2^21043843771 is an apocalyptic number.

21043843771 is a deficient number, since it is larger than the sum of its proper divisors (1503209093).

21043843771 is a wasteful number, since it uses less digits than its factorization.

21043843771 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20310.

The product of its (nonzero) digits is 112896, while the sum is 40.

The spelling of 21043843771 in words is "twenty-one billion, forty-three million, eight hundred forty-three thousand, seven hundred seventy-one".