661787390 has 32 divisors (see below), whose sum is σ = 1375955424. Its totient is φ = 226493440.

The previous prime is 661787389. The next prime is 661787393. The reversal of 661787390 is 93787166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661787393) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 175079 + ... + 178818.

It is an arithmetic number, because the mean of its divisors is an integer number (42998607).

Almost surely, 2^661787390 is an apocalyptic number.

661787390 is an abundant number, since it is smaller than the sum of its proper divisors (714168034).

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

661787390 is a wasteful number, since it uses less digits than its factorization.

661787390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353932.

The product of its (nonzero) digits is 381024, while the sum is 47.

The square root of 661787390 is about 25725.2286675940. The cubic root of 661787390 is about 871.4440236955. Note that the first 3 decimals are identical.

The spelling of 661787390 in words is "six hundred sixty-one million, seven hundred eighty-seven thousand, three hundred ninety".