661245500 has 96 divisors (see below), whose sum is σ = 1532364288. Its totient is φ = 248832000.

The previous prime is 661245493. The next prime is 661245503. The reversal of 661245500 is 5542166.

It is a super-2 number, since 2×661245500² = 874491222540500000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661245503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 572924 + ... + 574076.

It is an arithmetic number, because the mean of its divisors is an integer number (15962128).

Almost surely, 2^661245500 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661245500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (766182144).

661245500 is an abundant number, since it is smaller than the sum of its proper divisors (871118788).

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

661245500 is a wasteful number, since it uses less digits than its factorization.

661245500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1240 (or 1228 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 661245500 is about 25714.6942427866. The cubic root of 661245500 is about 871.2061045094.

Adding to 661245500 its reverse (5542166), we get a palindrome (666787666).

The spelling of 661245500 in words is "six hundred sixty-one million, two hundred forty-five thousand, five hundred".