211631640 has 128 divisors (see below), whose sum is σ = 733432320. Its totient is φ = 48281600.

The previous prime is 211631611. The next prime is 211631653. The reversal of 211631640 is 46136112.

211631640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 211631640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17725 + ... + 27155.

It is an arithmetic number, because the mean of its divisors is an integer number (5729940).

Almost surely, 2^211631640 is an apocalyptic number.

211631640 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 211631640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (366716160).

211631640 is an abundant number, since it is smaller than the sum of its proper divisors (521800680).

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

211631640 is a wasteful number, since it uses less digits than its factorization.

211631640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9473 (or 9469 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 211631640 is about 14547.5647446574. The cubic root of 211631640 is about 595.9276446253.

Adding to 211631640 its reverse (46136112), we get a palindrome (257767752).

The spelling of 211631640 in words is "two hundred eleven million, six hundred thirty-one thousand, six hundred forty".