997991215 has 32 divisors (see below), whose sum is σ = 1335269376. Its totient is φ = 711089280.

The previous prime is 997991213. The next prime is 997991221. The reversal of 997991215 is 512199799.

It is a happy number.

It is not a de Polignac number, because 997991215 - 2¹ = 997991213 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 (997991213) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1053372 + ... + 1054318.

It is an arithmetic number, because the mean of its divisors is an integer number (41727168).

Almost surely, 2^997991215 is an apocalyptic number.

997991215 is a deficient number, since it is larger than the sum of its proper divisors (337278161).

997991215 is a wasteful number, since it uses less digits than its factorization.

997991215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1519.

The product of its digits is 459270, while the sum is 52.

The square root of 997991215 is about 31590.9989553987. The cubic root of 997991215 is about 999.3299561415.

The spelling of 997991215 in words is "nine hundred ninety-seven million, nine hundred ninety-one thousand, two hundred fifteen".