661245624 has 144 divisors (see below), whose sum is σ = 2002927680. Its totient is φ = 196784640.

The previous prime is 661245577. The next prime is 661245643. The reversal of 661245624 is 426542166.

661245624 is a `hidden beast` number, since 6 + 6 + 1 + 24 + 5 + 624 = 666.

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

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 376332 + ... + 378084.

It is an arithmetic number, because the mean of its divisors is an integer number (13909220).

Almost surely, 2^661245624 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 661245624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1001463840).

661245624 is an abundant number, since it is smaller than the sum of its proper divisors (1341682056).

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

661245624 is a wasteful number, since it uses less digits than its factorization.

661245624 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1822 (or 1802 counting only the distinct ones).

The product of its digits is 69120, while the sum is 36.

The square root of 661245624 is about 25714.6966538592. The cubic root of 661245624 is about 871.2061589671.

The spelling of 661245624 in words is "six hundred sixty-one million, two hundred forty-five thousand, six hundred twenty-four".