172403821 has 2 divisors, whose sum is σ = 172403822. Its totient is φ = 172403820.

The previous prime is 172403807. The next prime is 172403909. The reversal of 172403821 is 128304271.

172403821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 145467721 + 26936100 = 12061^2 + 5190^2 .

It is a cyclic number.

It is not a de Polignac number, because 172403821 - 2¹¹ = 172401773 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 172403821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172403801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86201910 + 86201911.

It is an arithmetic number, because the mean of its divisors is an integer number (86201911).

Almost surely, 2^172403821 is an apocalyptic number.

It is an amenable number.

172403821 is a deficient number, since it is larger than the sum of its proper divisors (1).

172403821 is an equidigital number, since it uses as much as digits as its factorization.

172403821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 172403821 is about 13130.2635540952. The cubic root of 172403821 is about 556.5646630045.

The spelling of 172403821 in words is "one hundred seventy-two million, four hundred three thousand, eight hundred twenty-one".