661763520 has 420 divisors, whose sum is σ = 2599727592. Its totient is φ = 159667200.

The previous prime is 661763519. The next prime is 661763533. The reversal of 661763520 is 25367166.

661763520 is a `hidden beast` number, since 6 + 6 + 17 + 635 + 2 + 0 = 666.

661763520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 59 ways as a sum of consecutive naturals, for example, 3136215 + ... + 3136425.

Almost surely, 2^661763520 is an apocalyptic number.

661763520 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 661763520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1299863796).

661763520 is an abundant number, since it is smaller than the sum of its proper divisors (1937964072).

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

661763520 is a wasteful number, since it uses less digits than its factorization.

661763520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 45360, while the sum is 36.

The square root of 661763520 is about 25724.7647219562. The cubic root of 661763520 is about 871.4335462021.

It can be divided in two parts, 66176 and 3520, that added together give a palindrome (69696).

The spelling of 661763520 in words is "six hundred sixty-one million, seven hundred sixty-three thousand, five hundred twenty".