216409865555520 has 1792 divisors, whose sum is σ = 971948678400000. Its totient is φ = 45034037379072.

The previous prime is 216409865555497. The next prime is 216409865555531. The reversal of 216409865555520 is 25555568904612.

It is a happy number.

216409865555520 is a `hidden beast` number, since 2 + 1 + 6 + 4 + 0 + 9 + 8 + 6 + 55 + 55 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 2812342006 + ... + 2812418954.

It is an arithmetic number, because the mean of its divisors is an integer number (542382075000).

Almost surely, 2^{216409865555520} is an apocalyptic number.

216409865555520 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 216409865555520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (485974339200000).

216409865555520 is an abundant number, since it is smaller than the sum of its proper divisors (755538812844480).

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

216409865555520 is a wasteful number, since it uses less digits than its factorization.

216409865555520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77082 (or 77052 counting only the distinct ones).

The product of its (nonzero) digits is 129600000, while the sum is 63.

The spelling of 216409865555520 in words is "two hundred sixteen trillion, four hundred nine billion, eight hundred sixty-five million, five hundred fifty-five thousand, five hundred twenty".