1561006566 has 80 divisors (see below), whose sum is σ = 4010029056. Its totient is φ = 444604464.

The previous prime is 1561006561. The next prime is 1561006609. The reversal of 1561006566 is 6656001651.

It is a super-2 number, since 2×1561006566² = 4873482998190224712, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1561006566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561006561) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 391515 + ... + 395481.

Almost surely, 2^1561006566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561006566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2005014528).

1561006566 is an abundant number, since it is smaller than the sum of its proper divisors (2449022490).

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

1561006566 is a wasteful number, since it uses less digits than its factorization.

1561006566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4335 (or 4326 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 1561006566 is about 39509.5756241446. The cubic root of 1561006566 is about 1160.0273888698.

The spelling of 1561006566 in words is "one billion, five hundred sixty-one million, six thousand, five hundred sixty-six".