217953431 has 2 divisors, whose sum is σ = 217953432. Its totient is φ = 217953430.

The previous prime is 217953409. The next prime is 217953433. The reversal of 217953431 is 134359712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 217953431 - 2⁶ = 217953367 is a prime.

It is a super-2 number, since 2×217953431² = 95007396169343522, which contains 22 as substring.

Together with 217953433, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 217953391 and 217953400.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217953433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108976715 + 108976716.

It is an arithmetic number, because the mean of its divisors is an integer number (108976716).

Almost surely, 2^217953431 is an apocalyptic number.

217953431 is a deficient number, since it is larger than the sum of its proper divisors (1).

217953431 is an equidigital number, since it uses as much as digits as its factorization.

217953431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 35.

The square root of 217953431 is about 14763.2459506709. The cubic root of 217953431 is about 601.8033071167.

The spelling of 217953431 in words is "two hundred seventeen million, nine hundred fifty-three thousand, four hundred thirty-one".