216979540 has 24 divisors (see below), whose sum is σ = 470356992. Its totient is φ = 83991840.

The previous prime is 216979531. The next prime is 216979547. The reversal of 216979540 is 45979612.

It is a happy number.

It is a super-2 number, since 2×216979540² = 94160241557223200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216979547) 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, 174364 + ... + 175603.

It is an arithmetic number, because the mean of its divisors is an integer number (19598208).

Almost surely, 2^216979540 is an apocalyptic number.

216979540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216979540 is an abundant number, since it is smaller than the sum of its proper divisors (253377452).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

216979540 is a wasteful number, since it uses less digits than its factorization.

216979540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350007 (or 350005 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 43.

The square root of 216979540 is about 14730.2253886354. The cubic root of 216979540 is about 600.9056138995.

The spelling of 216979540 in words is "two hundred sixteen million, nine hundred seventy-nine thousand, five hundred forty".