216973491 has 8 divisors (see below), whose sum is σ = 330626304. Its totient is φ = 123984840.

The previous prime is 216973489. The next prime is 216973501. The reversal of 216973491 is 194379612.

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

It is not a de Polignac number, because 216973491 - 2¹ = 216973489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216973441) 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, 5166015 + ... + 5166056.

It is an arithmetic number, because the mean of its divisors is an integer number (41328288).

Almost surely, 2^216973491 is an apocalyptic number.

216973491 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

216973491 is a deficient number, since it is larger than the sum of its proper divisors (113652813).

216973491 is a wasteful number, since it uses less digits than its factorization.

216973491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10332081.

The product of its digits is 81648, while the sum is 42.

The square root of 216973491 is about 14730.0200610861. The cubic root of 216973491 is about 600.9000297911.

The spelling of 216973491 in words is "two hundred sixteen million, nine hundred seventy-three thousand, four hundred ninety-one".