394431478981 has 8 divisors (see below), whose sum is σ = 403541120664. Its totient is φ = 385383598080.

The previous prime is 394431478967. The next prime is 394431478993. The reversal of 394431478981 is 189874134493.

It can be written as a sum of positive squares in 4 ways, for example, as 188038445956 + 206393033025 = 433634^2 + 454305^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-394431478981 is a prime.

It is a super-2 number, since 2×394431478981² (a number of 24 digits) 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 (394431448981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15427276 + ... + 15452821.

It is an arithmetic number, because the mean of its divisors is an integer number (50442640083).

Almost surely, 2^394431478981 is an apocalyptic number.

It is an amenable number.

394431478981 is a deficient number, since it is larger than the sum of its proper divisors (9109641683).

394431478981 is a wasteful number, since it uses less digits than its factorization.

394431478981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30880391.

The product of its digits is 20901888, while the sum is 61.

The spelling of 394431478981 in words is "three hundred ninety-four billion, four hundred thirty-one million, four hundred seventy-eight thousand, nine hundred eighty-one".