211661242420 has 36 divisors (see below), whose sum is σ = 448457487660. Its totient is φ = 83915152384.

The previous prime is 211661242411. The next prime is 211661242421. The reversal of 211661242420 is 24242166112.

It can be written as a sum of positive squares in 6 ways, for example, as 116300096784 + 95361145636 = 341028^2 + 308806^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (211661242421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 159025 + ... + 669784.

It is an arithmetic number, because the mean of its divisors is an integer number (12457152435).

Almost surely, 2^211661242420 is an apocalyptic number.

211661242420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

211661242420 is an abundant number, since it is smaller than the sum of its proper divisors (236796245240).

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

211661242420 is a wasteful number, since it uses less digits than its factorization.

211661242420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 829044 (or 828929 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

The spelling of 211661242420 in words is "two hundred eleven billion, six hundred sixty-one million, two hundred forty-two thousand, four hundred twenty".