991444815 has 24 divisors (see below), whose sum is σ = 1720646928. Its totient is φ = 528111360.

The previous prime is 991444801. The next prime is 991444829. The reversal of 991444815 is 518444199.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (991444801) and next prime (991444829).

It is not a de Polignac number, because 991444815 - 2⁴ = 991444799 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23895 + ... + 50535.

It is an arithmetic number, because the mean of its divisors is an integer number (71693622).

Almost surely, 2^991444815 is an apocalyptic number.

991444815 is a deficient number, since it is larger than the sum of its proper divisors (729202113).

991444815 is a wasteful number, since it uses less digits than its factorization.

991444815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27479 (or 27476 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 991444815 is about 31487.2166918577. The cubic root of 991444815 is about 997.1401004382.

The spelling of 991444815 in words is "nine hundred ninety-one million, four hundred forty-four thousand, eight hundred fifteen".