661187715090 has 192 divisors, whose sum is σ = 1838266306560. Its totient is φ = 149088384000.

The previous prime is 661187715073. The next prime is 661187715091. The reversal of 661187715090 is 90517781166.

661187715090 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 not an unprimeable number, because it can be changed into a prime (661187715091) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1841748331 + ... + 1841748689.

It is an arithmetic number, because the mean of its divisors is an integer number (9574303680).

Almost surely, 2^661187715090 is an apocalyptic number.

It is a pronic number, being equal to 813134×813135.

It is a practical number, because each smaller number is the sum of distinct divisors of 661187715090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (919133153280).

661187715090 is an abundant number, since it is smaller than the sum of its proper divisors (1177078591470).

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

661187715090 is a wasteful number, since it uses less digits than its factorization.

661187715090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1009 (or 768 counting only the distinct ones).

The product of its (nonzero) digits is 635040, while the sum is 51.

The spelling of 661187715090 in words is "six hundred sixty-one billion, one hundred eighty-seven million, seven hundred fifteen thousand, ninety".