102121210120021 has 4 divisors (see below), whose sum is σ = 102121385276844. Its totient is φ = 102121034963200.

The previous prime is 102121210119961. The next prime is 102121210120099. The reversal of 102121210120021 is 120021012121201.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 85477143798225 + 16644066321796 = 9245385^2 + 4079714^2 .

It is a cyclic number.

It is not a de Polignac number, because 102121210120021 - 2¹¹ = 102121210117973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102121210119977 and 102121210120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102121210127021) 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 in 3 ways as a sum of consecutive naturals, for example, 86700940 + ... + 87870901.

It is an arithmetic number, because the mean of its divisors is an integer number (25530346319211).

Almost surely, 2^{102121210120021} is an apocalyptic number.

It is an amenable number.

102121210120021 is a deficient number, since it is larger than the sum of its proper divisors (175156823).

102121210120021 is an equidigital number, since it uses as much as digits as its factorization.

102121210120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175156822.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 102121210120021 its reverse (120021012121201), we get a palindrome (222142222241222).

The spelling of 102121210120021 in words is "one hundred two trillion, one hundred twenty-one billion, two hundred ten million, one hundred twenty thousand, twenty-one".