393987901 has 4 divisors (see below), whose sum is σ = 403597404. Its totient is φ = 384378400.

The previous prime is 393987883. The next prime is 393987917. The reversal of 393987901 is 109789393.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 109789393 = 7 ⋅15684199.

It can be written as a sum of positive squares in 2 ways, for example, as 157628025 + 236359876 = 12555^2 + 15374^2 .

It is a cyclic number.

It is not a de Polignac number, because 393987901 - 2¹¹ = 393985853 is a prime.

It is a super-2 number, since 2×393987901² = 310452932268771602, 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 (393987941) 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, 4804690 + ... + 4804771.

It is an arithmetic number, because the mean of its divisors is an integer number (100899351).

Almost surely, 2^393987901 is an apocalyptic number.

It is an amenable number.

393987901 is a deficient number, since it is larger than the sum of its proper divisors (9609503).

393987901 is an equidigital number, since it uses as much as digits as its factorization.

393987901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9609502.

The product of its (nonzero) digits is 367416, while the sum is 49.

The square root of 393987901 is about 19849.1284695324. The cubic root of 393987901 is about 733.0961888625.

The spelling of 393987901 in words is "three hundred ninety-three million, nine hundred eighty-seven thousand, nine hundred one".