991381213 has 8 divisors (see below), whose sum is σ = 1035384768. Its totient is φ = 947452704.

The previous prime is 991381201. The next prime is 991381217. The reversal of 991381213 is 312183199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991381213 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 (991381217) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9145 + ... + 45457.

It is an arithmetic number, because the mean of its divisors is an integer number (129423096).

Almost surely, 2^991381213 is an apocalyptic number.

It is an amenable number.

991381213 is a deficient number, since it is larger than the sum of its proper divisors (44003555).

991381213 is a wasteful number, since it uses less digits than its factorization.

991381213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37523.

The product of its digits is 11664, while the sum is 37.

The square root of 991381213 is about 31486.2067102406. The cubic root of 991381213 is about 997.1187775298.

The spelling of 991381213 in words is "nine hundred ninety-one million, three hundred eighty-one thousand, two hundred thirteen".