211785640 has 64 divisors (see below), whose sum is σ = 522936000. Its totient is φ = 76554240.

The previous prime is 211785631. The next prime is 211785641. The reversal of 211785640 is 46587112.

It is a junction number, because it is equal to n+sod(n) for n = 211785596 and 211785605.

It is not an unprimeable number, because it can be changed into a prime (211785641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77416 + ... + 80104.

It is an arithmetic number, because the mean of its divisors is an integer number (8170875).

Almost surely, 2^211785640 is an apocalyptic number.

211785640 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 211785640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (261468000).

211785640 is an abundant number, since it is smaller than the sum of its proper divisors (311150360).

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

211785640 is a wasteful number, since it uses less digits than its factorization.

211785640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2890 (or 2886 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 211785640 is about 14552.8567642233. The cubic root of 211785640 is about 596.0721576825.

The spelling of 211785640 in words is "two hundred eleven million, seven hundred eighty-five thousand, six hundred forty".