102172021 has 4 divisors (see below), whose sum is σ = 116768032. Its totient is φ = 87576012.

The previous prime is 102171991. The next prime is 102172039. The reversal of 102172021 is 120271201.

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: 120271201 = 37 ⋅3250573.

It is a cyclic number.

It is not a de Polignac number, because 102172021 - 2²⁵ = 68617589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102171986 and 102172004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102172051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7297995 + ... + 7298008.

It is an arithmetic number, because the mean of its divisors is an integer number (29192008).

Almost surely, 2^102172021 is an apocalyptic number.

It is an amenable number.

102172021 is a deficient number, since it is larger than the sum of its proper divisors (14596011).

102172021 is an equidigital number, since it uses as much as digits as its factorization.

102172021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14596010.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 102172021 is about 10108.0176592644. The cubic root of 102172021 is about 467.4953850098.

The spelling of 102172021 in words is "one hundred two million, one hundred seventy-two thousand, twenty-one".