1661011656 has 128 divisors (see below), whose sum is σ = 4608576000. Its totient is φ = 496484352.

The previous prime is 1661011637. The next prime is 1661011657. The reversal of 1661011656 is 6561101661.

It is not an unprimeable number, because it can be changed into a prime (1661011657) 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, 933840 + ... + 935616.

It is an arithmetic number, because the mean of its divisors is an integer number (36004500).

Almost surely, 2^1661011656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1661011656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2304288000).

1661011656 is an abundant number, since it is smaller than the sum of its proper divisors (2947564344).

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

1661011656 is a wasteful number, since it uses less digits than its factorization.

1661011656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1911 (or 1907 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 1661011656 is about 40755.5107439473. The cubic root of 1661011656 is about 1184.2886307074.

The spelling of 1661011656 in words is "one billion, six hundred sixty-one million, eleven thousand, six hundred fifty-six".