661091648 has 112 divisors (see below), whose sum is σ = 1614610944. Its totient is φ = 262103040.

The previous prime is 661091623. The next prime is 661091677. The reversal of 661091648 is 846190166.

661091648 is digitally balanced in base 2, because in such base 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 (112).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 463865 + ... + 465287.

Almost surely, 2^661091648 is an apocalyptic number.

661091648 is a gapful number since it is divisible by the number (68) 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 661091648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (807305472).

661091648 is an abundant number, since it is smaller than the sum of its proper divisors (953519296).

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

661091648 is a wasteful number, since it uses less digits than its factorization.

661091648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1520 (or 1510 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 41.

The square root of 661091648 is about 25711.7025496174. The cubic root of 661091648 is about 871.1385314228.

The spelling of 661091648 in words is "six hundred sixty-one million, ninety-one thousand, six hundred forty-eight".