661143800 has 24 divisors (see below), whose sum is σ = 1537159800. Its totient is φ = 264457440.

The previous prime is 661143781. The next prime is 661143823. The reversal of 661143800 is 8341166.

It is a super-2 number, since 2×661143800² = 874222248556880000, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1652660 + ... + 1653059.

It is an arithmetic number, because the mean of its divisors is an integer number (64048325).

Almost surely, 2^661143800 is an apocalyptic number.

It is an amenable number.

661143800 is an abundant number, since it is smaller than the sum of its proper divisors (876016000).

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

661143800 is a wasteful number, since it uses less digits than its factorization.

661143800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3305735 (or 3305726 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 661143800 is about 25712.7166981632. The cubic root of 661143800 is about 871.1614381923.

Adding to 661143800 its reverse (8341166), we get a palindrome (669484966).

The spelling of 661143800 in words is "six hundred sixty-one million, one hundred forty-three thousand, eight hundred".