400013391 has 16 divisors (see below), whose sum is σ = 546613760. Its totient is φ = 260064000.

The previous prime is 400013387. The next prime is 400013399. The reversal of 400013391 is 193310004.

It is not a de Polignac number, because 400013391 - 2² = 400013387 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 (400013399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94815 + ... + 98943.

It is an arithmetic number, because the mean of its divisors is an integer number (34163360).

Almost surely, 2^400013391 is an apocalyptic number.

400013391 is a deficient number, since it is larger than the sum of its proper divisors (146600369).

400013391 is a wasteful number, since it uses less digits than its factorization.

400013391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4926.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 400013391 is about 20000.3347721982. The cubic root of 400013391 is about 736.8145217806.

Adding to 400013391 its reverse (193310004), we get a palindrome (593323395).

It can be divided in two parts, 4000 and 13391, that added together give a triangular number (17391 = T₁₈₆).

The spelling of 400013391 in words is "four hundred million, thirteen thousand, three hundred ninety-one".