398947981 has 4 divisors (see below), whose sum is σ = 399002364. Its totient is φ = 398893600.

The previous prime is 398947979. The next prime is 398948047. The reversal of 398947981 is 189749893.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 126202756 + 272745225 = 11234^2 + 16515^2 .

It is a cyclic number.

It is not a de Polignac number, because 398947981 - 2¹ = 398947979 is a prime.

It is a super-2 number, since 2×398947981² = 318318983087952722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398947951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14080 + ... + 31561.

It is an arithmetic number, because the mean of its divisors is an integer number (99750591).

Almost surely, 2^398947981 is an apocalyptic number.

It is an amenable number.

398947981 is a deficient number, since it is larger than the sum of its proper divisors (54383).

398947981 is an equidigital number, since it uses as much as digits as its factorization.

398947981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54382.

The product of its digits is 3919104, while the sum is 58.

The square root of 398947981 is about 19973.6822093474. The cubic root of 398947981 is about 736.1597874215.

The spelling of 398947981 in words is "three hundred ninety-eight million, nine hundred forty-seven thousand, nine hundred eighty-one".