102121220021 has 4 divisors (see below), whose sum is σ = 103795338444. Its totient is φ = 100447101600.

The previous prime is 102121220017. The next prime is 102121220029. The reversal of 102121220021 is 120022121201.

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 41499393796 + 60621826225 = 203714^2 + 246215^2 .

It is a cyclic number.

It is not a de Polignac number, because 102121220021 - 2² = 102121220017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102121219978 and 102121220005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102121220029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 837059120 + ... + 837059241.

It is an arithmetic number, because the mean of its divisors is an integer number (25948834611).

Almost surely, 2^102121220021 is an apocalyptic number.

It is an amenable number.

102121220021 is a deficient number, since it is larger than the sum of its proper divisors (1674118423).

102121220021 is an equidigital number, since it uses as much as digits as its factorization.

102121220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1674118422.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 102121220021 its reverse (120022121201), we get a palindrome (222143341222).

The spelling of 102121220021 in words is "one hundred two billion, one hundred twenty-one million, two hundred twenty thousand, twenty-one".