21784874389 has 2 divisors, whose sum is σ = 21784874390. Its totient is φ = 21784874388.

The previous prime is 21784874323. The next prime is 21784874431. The reversal of 21784874389 is 98347848712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13494771889 + 8290102500 = 116167^2 + 91050^2 .

It is a cyclic number.

It is not a de Polignac number, because 21784874389 - 2¹¹ = 21784872341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21784874789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10892437194 + 10892437195.

It is an arithmetic number, because the mean of its divisors is an integer number (10892437195).

Almost surely, 2^21784874389 is an apocalyptic number.

It is an amenable number.

21784874389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21784874389 is an equidigital number, since it uses as much as digits as its factorization.

21784874389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21676032, while the sum is 61.

The spelling of 21784874389 in words is "twenty-one billion, seven hundred eighty-four million, eight hundred seventy-four thousand, three hundred eighty-nine".