217392021 has 72 divisors (see below), whose sum is σ = 409945536. Its totient is φ = 107838720.

The previous prime is 217392013. The next prime is 217392101. The reversal of 217392021 is 120293712.

It is not a de Polignac number, because 217392021 - 2³ = 217392013 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217392001) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 366301 + ... + 366893.

It is an arithmetic number, because the mean of its divisors is an integer number (5693688).

Almost surely, 2^217392021 is an apocalyptic number.

217392021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

217392021 is a deficient number, since it is larger than the sum of its proper divisors (192553515).

217392021 is a wasteful number, since it uses less digits than its factorization.

217392021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 663 (or 637 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 217392021 is about 14744.2199183273. The cubic root of 217392021 is about 601.2861493963.

The spelling of 217392021 in words is "two hundred seventeen million, three hundred ninety-two thousand, twenty-one".