3998720405 has 4 divisors (see below), whose sum is σ = 4798464492. Its totient is φ = 3198976320.

The previous prime is 3998720389. The next prime is 3998720413. The reversal of 3998720405 is 5040278993.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5040278993 = 49727 ⋅101359.

It can be written as a sum of positive squares in 2 ways, for example, as 597264721 + 3401455684 = 24439^2 + 58322^2 .

It is not a de Polignac number, because 3998720405 - 2⁴ = 3998720389 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 3998720405.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 399872036 + ... + 399872045.

It is an arithmetic number, because the mean of its divisors is an integer number (1199616123).

Almost surely, 2^3998720405 is an apocalyptic number.

It is an amenable number.

3998720405 is a deficient number, since it is larger than the sum of its proper divisors (799744087).

3998720405 is an equidigital number, since it uses as much as digits as its factorization.

3998720405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 799744086.

The product of its (nonzero) digits is 544320, while the sum is 47.

The square root of 3998720405 is about 63235.4363075009. The cubic root of 3998720405 is about 1587.2317647112.

The spelling of 3998720405 in words is "three billion, nine hundred ninety-eight million, seven hundred twenty thousand, four hundred five".