1561040100 has 135 divisors (see below), whose sum is σ = 5071828377. Its totient is φ = 415329120.

The previous prime is 1561040083. The next prime is 1561040141. The reversal of 1561040100 is 10401651.

The square root of 1561040100 is 39510.

It is a perfect power (a square), and thus also a powerful number.

1561040100 is a `hidden beast` number, since 1 + 5 + 610 + 40 + 10 + 0 = 666.

It can be written as a sum of positive squares in only one way, i.e., 561974436 + 999065664 = 23706^2 + 31608^2 .

It is a tau number, because it is divible by the number of its divisors (135).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 3555681 + ... + 3556119.

Almost surely, 2^1561040100 is an apocalyptic number.

1561040100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1561040100 is the 39510-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561040100

1561040100 is an abundant number, since it is smaller than the sum of its proper divisors (3510788277).

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

1561040100 is an equidigital number, since it uses as much as digits as its factorization.

1561040100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 904 (or 449 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The cubic root of 1561040100 is about 1160.0356954929.

Adding to 1561040100 its reverse (10401651), we get a palindrome (1571441751).

The spelling of 1561040100 in words is "one billion, five hundred sixty-one million, forty thousand, one hundred".