212345640 has 288 divisors, whose sum is σ = 794528280. Its totient is φ = 48881664.

The previous prime is 212345621. The next prime is 212345647. The reversal of 212345640 is 46543212.

212345640 is a `hidden beast` number, since 2 + 12 + 3 + 4 + 5 + 640 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 20412324 + 191933316 = 4518^2 + 13854^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212345647) 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, 1352442 + ... + 1352598.

Almost surely, 2^212345640 is an apocalyptic number.

212345640 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 212345640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (397264140).

212345640 is an abundant number, since it is smaller than the sum of its proper divisors (582182640).

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

212345640 is a wasteful number, since it uses less digits than its factorization.

212345640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 212345640 is about 14572.0842709614. The cubic root of 212345640 is about 596.5970699317.

Adding to 212345640 its reverse (46543212), we get a palindrome (258888852).

The spelling of 212345640 in words is "two hundred twelve million, three hundred forty-five thousand, six hundred forty".