172821400 has 24 divisors (see below), whose sum is σ = 401810220. Its totient is φ = 69128480.

The previous prime is 172821391. The next prime is 172821421. The reversal of 172821400 is 4128271.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 431854 + ... + 432253.

Almost surely, 2^172821400 is an apocalyptic number.

172821400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

172821400 is an abundant number, since it is smaller than the sum of its proper divisors (228988820).

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

172821400 is a wasteful number, since it uses less digits than its factorization.

172821400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864123 (or 864114 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 172821400 is about 13146.1553315028. The cubic root of 172821400 is about 557.0136521402.

Adding to 172821400 its reverse (4128271), we get a palindrome (176949671).

The spelling of 172821400 in words is "one hundred seventy-two million, eight hundred twenty-one thousand, four hundred".