216251971 has 4 divisors (see below), whose sum is σ = 232886752. Its totient is φ = 199617192.

The previous prime is 216251963. The next prime is 216251989. The reversal of 216251971 is 179152612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216251971 - 2³ = 216251963 is a prime.

It is a super-2 number, since 2×216251971² = 93529829922769682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216251921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8317371 + ... + 8317396.

It is an arithmetic number, because the mean of its divisors is an integer number (58221688).

Almost surely, 2^216251971 is an apocalyptic number.

216251971 is a deficient number, since it is larger than the sum of its proper divisors (16634781).

216251971 is a wasteful number, since it uses less digits than its factorization.

216251971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16634780.

The product of its digits is 7560, while the sum is 34.

The square root of 216251971 is about 14705.5081857106. The cubic root of 216251971 is about 600.2332158204.

The spelling of 216251971 in words is "two hundred sixteen million, two hundred fifty-one thousand, nine hundred seventy-one".