21402179889949 has 2 divisors, whose sum is σ = 21402179889950. Its totient is φ = 21402179889948.

The previous prime is 21402179889869. The next prime is 21402179889977. The reversal of 21402179889949 is 94998897120412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15756414219225 + 5645765670724 = 3969435^2 + 2376082^2 .

It is a cyclic number.

It is not a de Polignac number, because 21402179889949 - 2¹¹ = 21402179887901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21402179889989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701089944974 + 10701089944975.

It is an arithmetic number, because the mean of its divisors is an integer number (10701089944975).

Almost surely, 2^{21402179889949} is an apocalyptic number.

It is an amenable number.

21402179889949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402179889949 is an equidigital number, since it uses as much as digits as its factorization.

21402179889949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 188116992, while the sum is 73.

The spelling of 21402179889949 in words is "twenty-one trillion, four hundred two billion, one hundred seventy-nine million, eight hundred eighty-nine thousand, nine hundred forty-nine".