21000021004939 has 2 divisors, whose sum is σ = 21000021004940. Its totient is φ = 21000021004938.

The previous prime is 21000021004883. The next prime is 21000021004967. The reversal of 21000021004939 is 93940012000012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21000021004939 - 2³¹ = 20997873521291 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21000021004939.

It is not a weakly prime, because it can be changed into another prime (21000021007939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500010502469 + 10500010502470.

It is an arithmetic number, because the mean of its divisors is an integer number (10500010502470).

Almost surely, 2^{21000021004939} is an apocalyptic number.

21000021004939 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000021004939 is an equidigital number, since it uses as much as digits as its factorization.

21000021004939 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 31.

The spelling of 21000021004939 in words is "twenty-one trillion, twenty-one million, four thousand, nine hundred thirty-nine".