661415100 has 72 divisors (see below), whose sum is σ = 1917512688. Its totient is φ = 176025600.

The previous prime is 661415081. The next prime is 661415119. The reversal of 661415100 is 1514166.

It is an interprime number because it is at equal distance from previous prime (661415081) and next prime (661415119).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 171190 + ... + 175010.

Almost surely, 2^661415100 is an apocalyptic number.

661415100 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661415100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (958756344).

661415100 is an abundant number, since it is smaller than the sum of its proper divisors (1256097588).

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

661415100 is a wasteful number, since it uses less digits than its factorization.

661415100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4415 (or 4408 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 661415100 is about 25717.9917567449. The cubic root of 661415100 is about 871.2805821049.

Adding to 661415100 its reverse (1514166), we get a palindrome (662929266).

The spelling of 661415100 in words is "six hundred sixty-one million, four hundred fifteen thousand, one hundred".