398920729 has 3 divisors (see below), whose sum is σ = 398940703. Its totient is φ = 398900756.

The previous prime is 398920727. The next prime is 398920757. The reversal of 398920729 is 927029893.

The square root of 398920729 is 19973.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 150921225 + 247999504 = 12285^2 + 15748^2 .

It is not a de Polignac number, because 398920729 - 2¹ = 398920727 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (398920721) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 9987 + ... + 29959.

Almost surely, 2^398920729 is an apocalyptic number.

398920729 is the 19973-rd square number.

398920729 is the 9987-th centered octagonal number.

It is an amenable number.

398920729 is a deficient number, since it is larger than the sum of its proper divisors (19974).

398920729 is an frugal number, since it uses more digits than its factorization.

398920729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39946 (or 19973 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 49.

The cubic root of 398920729 is about 736.1430247655.

Multiplying 398920729 by its sum of digits (49), we get a square (19547115721 = 139811²).

The spelling of 398920729 in words is "three hundred ninety-eight million, nine hundred twenty thousand, seven hundred twenty-nine".