1001561000 has 128 divisors (see below), whose sum is σ = 2589874560. Its totient is φ = 359488000.

The previous prime is 1001560999. The next prime is 1001561017. The reversal of 1001561000 is 1651001.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 912452 + ... + 913548.

It is an arithmetic number, because the mean of its divisors is an integer number (20233395).

Almost surely, 2^1001561000 is an apocalyptic number.

1001561000 is a gapful number since it is divisible by the number (10) 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 1001561000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1294937280).

1001561000 is an abundant number, since it is smaller than the sum of its proper divisors (1588313560).

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

1001561000 is a wasteful number, since it uses less digits than its factorization.

1001561000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1212 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 1001561000 is about 31647.4485543464. The cubic root of 1001561000 is about 1000.5200628211.

Subtracting from 1001561000 its reverse (1651001), we obtain a palindrome (999909999).

The spelling of 1001561000 in words is "one billion, one million, five hundred sixty-one thousand".