399240603661 has 4 divisors (see below), whose sum is σ = 400150036000. Its totient is φ = 398331171324.

The previous prime is 399240603637. The next prime is 399240603673. The reversal of 399240603661 is 166306042993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 166306042993 = 51133 ⋅3252421.

It is a cyclic number.

It is not a de Polignac number, because 399240603661 - 2⁷ = 399240603533 is a prime.

It is a super-3 number, since 3×399240603661³ (a number of 36 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399240609661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 454715511 + ... + 454716388.

It is an arithmetic number, because the mean of its divisors is an integer number (100037509000).

Almost surely, 2^399240603661 is an apocalyptic number.

It is an amenable number.

399240603661 is a deficient number, since it is larger than the sum of its proper divisors (909432339).

399240603661 is an equidigital number, since it uses as much as digits as its factorization.

399240603661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 909432338.

The product of its (nonzero) digits is 1259712, while the sum is 49.

The spelling of 399240603661 in words is "three hundred ninety-nine billion, two hundred forty million, six hundred three thousand, six hundred sixty-one".