661812 has 24 divisors (see below), whose sum is σ = 1559712. Its totient is φ = 218400.

The previous prime is 661777. The next prime is 661823. The reversal of 661812 is 218166.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 661812.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1362 + ... + 1782.

It is an arithmetic number, because the mean of its divisors is an integer number (64988).

2⁶⁶¹⁸¹² is an apocalyptic number.

It is an amenable number.

661812 is an abundant number, since it is smaller than the sum of its proper divisors (897900).

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

661812 is a wasteful number, since it uses less digits than its factorization.

661812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 559 (or 557 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 661812 is about 813.5182849820. The cubic root of 661812 is about 87.1454825741.

Adding to 661812 its reverse (218166), we get a palindrome (879978).

The spelling of 661812 in words is "six hundred sixty-one thousand, eight hundred twelve".