172821870 has 128 divisors (see below), whose sum is σ = 506217600. Its totient is φ = 41693184.

The previous prime is 172821851. The next prime is 172821889. The reversal of 172821870 is 78128271.

It is a happy number.

172821870 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (172821851) and next prime (172821889).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 185566 + ... + 186494.

It is an arithmetic number, because the mean of its divisors is an integer number (3954825).

Almost surely, 2^172821870 is an apocalyptic number.

172821870 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 172821870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (253108800).

172821870 is an abundant number, since it is smaller than the sum of its proper divisors (333395730).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

172821870 is a wasteful number, since it uses less digits than its factorization.

172821870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011 (or 1005 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The square root of 172821870 is about 13146.1732074395. The cubic root of 172821870 is about 557.0141570857.

The spelling of 172821870 in words is "one hundred seventy-two million, eight hundred twenty-one thousand, eight hundred seventy".