661642212 has 48 divisors (see below), whose sum is σ = 1924780032. Its totient is φ = 171854880.

The previous prime is 661642211. The next prime is 661642229. The reversal of 661642212 is 212246166.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 661642212.

It is not an unprimeable number, because it can be changed into a prime (661642211) 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, 357108 + ... + 358955.

It is an arithmetic number, because the mean of its divisors is an integer number (40099584).

Almost surely, 2^661642212 is an apocalyptic number.

It is an amenable number.

661642212 is an abundant number, since it is smaller than the sum of its proper divisors (1263137820).

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

661642212 is a wasteful number, since it uses less digits than its factorization.

661642212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716088 (or 716086 counting only the distinct ones).

The product of its digits is 6912, while the sum is 30.

The square root of 661642212 is about 25722.4068080730. The cubic root of 661642212 is about 871.3802953971.

Adding to 661642212 its reverse (212246166), we get a palindrome (873888378).

It can be divided in two parts, 6616 and 42212, that added together give a triangular number (48828 = T₃₁₂).

The spelling of 661642212 in words is "six hundred sixty-one million, six hundred forty-two thousand, two hundred twelve".