388239901921 has 9 divisors (see below), whose sum is σ = 392707255033. Its totient is φ = 383822824000.

The previous prime is 388239901909. The next prime is 388239901937. The reversal of 388239901921 is 129109932883.

The square root of 388239901921 is 623089.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 61559068321 + 326680833600 = 248111^2 + 571560^2 .

It is not a de Polignac number, because 388239901921 - 2⁹ = 388239901409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (388239908921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 55451421 + ... + 55458421.

Almost surely, 2^388239901921 is an apocalyptic number.

388239901921 is the 623089-th square number.

388239901921 is the 311545-th centered octagonal number.

It is an amenable number.

388239901921 is a deficient number, since it is larger than the sum of its proper divisors (4467353112).

388239901921 is an frugal number, since it uses more digits than its factorization.

388239901921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14180 (or 7090 counting only the distinct ones).

The product of its (nonzero) digits is 1679616, while the sum is 55.

The spelling of 388239901921 in words is "three hundred eighty-eight billion, two hundred thirty-nine million, nine hundred one thousand, nine hundred twenty-one".