661149720 has 768 divisors, whose sum is σ = 3008378880. Its totient is φ = 121651200.

The previous prime is 661149701. The next prime is 661149773. The reversal of 661149720 is 27941166.

661149720 is nontrivially palindromic in base 13.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 10838490 + ... + 10838550.

It is an arithmetic number, because the mean of its divisors is an integer number (3917160).

Almost surely, 2^661149720 is an apocalyptic number.

661149720 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 661149720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1504189440).

661149720 is an abundant number, since it is smaller than the sum of its proper divisors (2347229160).

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

661149720 is a wasteful number, since it uses less digits than its factorization.

661149720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136 (or 129 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 661149720 is about 25712.8318160408. The cubic root of 661149720 is about 871.1640383631.

The spelling of 661149720 in words is "six hundred sixty-one million, one hundred forty-nine thousand, seven hundred twenty".