217978942 has 8 divisors (see below), whose sum is σ = 328271832. Its totient is φ = 108555000.

The previous prime is 217978927. The next prime is 217978979. The reversal of 217978942 is 249879712.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 216609 + ... + 217612.

It is an arithmetic number, because the mean of its divisors is an integer number (41033979).

Almost surely, 2^217978942 is an apocalyptic number.

217978942 is a deficient number, since it is larger than the sum of its proper divisors (110292890).

217978942 is a wasteful number, since it uses less digits than its factorization.

217978942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434474.

The product of its digits is 508032, while the sum is 49.

The square root of 217978942 is about 14764.1099291491. The cubic root of 217978942 is about 601.8267861463.

The spelling of 217978942 in words is "two hundred seventeen million, nine hundred seventy-eight thousand, nine hundred forty-two".