388997947809 has 27 divisors (see below), whose sum is σ = 566691236787. Its totient is φ = 257132809584.

The previous prime is 388997947801. The next prime is 388997947837. The reversal of 388997947809 is 908749799883.

The square root of 388997947809 is 623697.

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

388997947809 is a `hidden beast` number, since 388 + 99 + 79 + 4 + 7 + 80 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11790702225 + 377207245584 = 108585^2 + 614172^2 .

It is not a de Polignac number, because 388997947809 - 2³ = 388997947801 is a prime.

It is a super-2 number, since 2×388997947809² (a number of 24 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (388997947801) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 237627739 + ... + 237629375.

Almost surely, 2^388997947809 is an apocalyptic number.

388997947809 is the 623697-th square number.

388997947809 is the 311849-th centered octagonal number.

It is an amenable number.

388997947809 is a deficient number, since it is larger than the sum of its proper divisors (177693288978).

388997947809 is an frugal number, since it uses more digits than its factorization.

388997947809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3534 (or 1767 counting only the distinct ones).

The product of its (nonzero) digits is 1975228416, while the sum is 81.

Multiplying 388997947809 by its sum of digits (81), we get a square (31508833772529 = 5613273²).

The spelling of 388997947809 in words is "three hundred eighty-eight billion, nine hundred ninety-seven million, nine hundred forty-seven thousand, eight hundred nine".