172010021 has 4 divisors (see below), whose sum is σ = 181063200. Its totient is φ = 162956844.

The previous prime is 172009997. The next prime is 172010053. The reversal of 172010021 is 120010271.

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.

It is not a de Polignac number, because 172010021 - 2¹⁰ = 172008997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 172009978 and 172010005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172010071) 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, 4526561 + ... + 4526598.

It is an arithmetic number, because the mean of its divisors is an integer number (45265800).

Almost surely, 2^172010021 is an apocalyptic number.

It is an amenable number.

172010021 is a deficient number, since it is larger than the sum of its proper divisors (9053179).

172010021 is an equidigital number, since it uses as much as digits as its factorization.

172010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9053178.

The product of its (nonzero) digits is 28, while the sum is 14.

The square root of 172010021 is about 13115.2590900828. The cubic root of 172010021 is about 556.1405767844.

Adding to 172010021 its reverse (120010271), we get a palindrome (292020292).

The spelling of 172010021 in words is "one hundred seventy-two million, ten thousand, twenty-one".