661621528512 has 224 divisors, whose sum is σ = 2294616330240. Its totient is φ = 182936724480.

The previous prime is 661621528417. The next prime is 661621528517. The reversal of 661621528512 is 215825126166.

661621528512 is a `hidden beast` number, since 6 + 6 + 1 + 621 + 5 + 2 + 8 + 5 + 12 = 666.

661621528512 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661621528517) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 507243 + ... + 1257194.

Almost surely, 2^661621528512 is an apocalyptic number.

661621528512 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is an amenable number.

661621528512 is an abundant number, since it is smaller than the sum of its proper divisors (1632994801728).

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

661621528512 is a wasteful number, since it uses less digits than its factorization.

661621528512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1764496 (or 1764480 counting only the distinct ones).

The product of its digits is 345600, while the sum is 45.

The spelling of 661621528512 in words is "six hundred sixty-one billion, six hundred twenty-one million, five hundred twenty-eight thousand, five hundred twelve".