217969920 has 576 divisors, whose sum is σ = 953648640. Its totient is φ = 46006272.

The previous prime is 217969901. The next prime is 217969933. The reversal of 217969920 is 29969712.

It is a tau number, because it is divible by the number of its divisors (576).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4112614 + ... + 4112666.

It is an arithmetic number, because the mean of its divisors is an integer number (1655640).

Almost surely, 2^217969920 is an apocalyptic number.

217969920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217969920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (476824320).

217969920 is an abundant number, since it is smaller than the sum of its proper divisors (735678720).

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

217969920 is a wasteful number, since it uses less digits than its factorization.

217969920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107 (or 87 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 45.

The square root of 217969920 is about 14763.8043877586. The cubic root of 217969920 is about 601.8184829648.

The spelling of 217969920 in words is "two hundred seventeen million, nine hundred sixty-nine thousand, nine hundred twenty".