11931813 has 16 divisors (see below), whose sum is σ = 17733760. Its totient is φ = 7928928.

The previous prime is 11931811. The next prime is 11931817. The reversal of 11931813 is 31813911.

It is a happy number.

It is not a de Polignac number, because 11931813 - 2¹ = 11931811 is a prime.

It is a super-3 number, since 3×11931813³ (a number of 22 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11931811) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11856 + ... + 12822.

It is an arithmetic number, because the mean of its divisors is an integer number (1108360).

Almost surely, 2^11931813 is an apocalyptic number.

It is an amenable number.

11931813 is a deficient number, since it is larger than the sum of its proper divisors (5801947).

11931813 is an equidigital number, since it uses as much as digits as its factorization.

11931813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1433 (or 1427 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 11931813 is about 3454.2456484738. The cubic root of 11931813 is about 228.5083877300.

The spelling of 11931813 in words is "eleven million, nine hundred thirty-one thousand, eight hundred thirteen".