21020513149949 has 2 divisors, whose sum is σ = 21020513149950. Its totient is φ = 21020513149948.

The previous prime is 21020513149877. The next prime is 21020513150059. The reversal of 21020513149949 is 94994131502012.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19707295704100 + 1313217445849 = 4439290^2 + 1145957^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020513149949 - 2⁸ = 21020513149693 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020513149897 and 21020513149906.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020513145949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510256574974 + 10510256574975.

It is an arithmetic number, because the mean of its divisors is an integer number (10510256574975).

Almost surely, 2^{21020513149949} is an apocalyptic number.

It is an amenable number.

21020513149949 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020513149949 is an equidigital number, since it uses as much as digits as its factorization.

21020513149949 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 699840, while the sum is 50.

The spelling of 21020513149949 in words is "twenty-one trillion, twenty billion, five hundred thirteen million, one hundred forty-nine thousand, nine hundred forty-nine".