21355555139 has 2 divisors, whose sum is σ = 21355555140. Its totient is φ = 21355555138.

The previous prime is 21355555103. The next prime is 21355555147. The reversal of 21355555139 is 93155555312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21355555139 - 2²⁴ = 21338777923 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21355555139.

It is not a weakly prime, because it can be changed into another prime (21355555339) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677777569 + 10677777570.

It is an arithmetic number, because the mean of its divisors is an integer number (10677777570).

Almost surely, 2^21355555139 is an apocalyptic number.

21355555139 is a deficient number, since it is larger than the sum of its proper divisors (1).

21355555139 is an equidigital number, since it uses as much as digits as its factorization.

21355555139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 506250, while the sum is 44.

The spelling of 21355555139 in words is "twenty-one billion, three hundred fifty-five million, five hundred fifty-five thousand, one hundred thirty-nine".