399402740509 has 4 divisors (see below), whose sum is σ = 399431544316. Its totient is φ = 399373936704.

The previous prime is 399402740447. The next prime is 399402740521. The reversal of 399402740509 is 905047204993.

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 277179084484 + 122223656025 = 526478^2 + 349605^2 .

It is a cyclic number.

It is not a de Polignac number, because 399402740509 - 2¹⁵ = 399402707741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399402744509) 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, 14381094 + ... + 14408839.

It is an arithmetic number, because the mean of its divisors is an integer number (99857886079).

Almost surely, 2^399402740509 is an apocalyptic number.

It is an amenable number.

399402740509 is a deficient number, since it is larger than the sum of its proper divisors (28803807).

399402740509 is a wasteful number, since it uses less digits than its factorization.

399402740509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28803806.

The product of its (nonzero) digits is 2449440, while the sum is 52.

The spelling of 399402740509 in words is "three hundred ninety-nine billion, four hundred two million, seven hundred forty thousand, five hundred nine".