102105021 has 4 divisors (see below), whose sum is σ = 136140032. Its totient is φ = 68070012.

The previous prime is 102105019. The next prime is 102105037. The reversal of 102105021 is 120501201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 120501201 = 3 ⋅40167067.

It is not a de Polignac number, because 102105021 - 2¹ = 102105019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102104988 and 102105006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102105121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17017501 + ... + 17017506.

It is an arithmetic number, because the mean of its divisors is an integer number (34035008).

Almost surely, 2^102105021 is an apocalyptic number.

It is an amenable number.

102105021 is a deficient number, since it is larger than the sum of its proper divisors (34035011).

102105021 is an equidigital number, since it uses as much as digits as its factorization.

102105021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34035010.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 102105021 is about 10104.7029149797. The cubic root of 102105021 is about 467.3931749019.

Adding to 102105021 its reverse (120501201), we get a palindrome (222606222).

The spelling of 102105021 in words is "one hundred two million, one hundred five thousand, twenty-one".