1011561661 has 8 divisors (see below), whose sum is σ = 1114236864. Its totient is φ = 910672320.

The previous prime is 1011561631. The next prime is 1011561701. The reversal of 1011561661 is 1661651101.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1011561661 - 2¹⁵ = 1011528893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1011561601) 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 7 ways as a sum of consecutive naturals, for example, 445276 + ... + 447541.

It is an arithmetic number, because the mean of its divisors is an integer number (139279608).

Almost surely, 2^1011561661 is an apocalyptic number.

1011561661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1011561661 is a deficient number, since it is larger than the sum of its proper divisors (102675203).

1011561661 is a wasteful number, since it uses less digits than its factorization.

1011561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 892931.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 1011561661 is about 31805.0571607724. The cubic root of 1011561661 is about 1003.8391292253.

The spelling of 1011561661 in words is "one billion, eleven million, five hundred sixty-one thousand, six hundred sixty-one".