1561268520 has 640 divisors, whose sum is σ = 6498455040. Its totient is φ = 328458240.

The previous prime is 1561268509. The next prime is 1561268549. The reversal of 1561268520 is 258621651.

1561268520 is a `hidden beast` number, since 1 + 5 + 6 + 126 + 8 + 520 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 21387204 + ... + 21387276.

It is an arithmetic number, because the mean of its divisors is an integer number (10153836).

Almost surely, 2^1561268520 is an apocalyptic number.

1561268520 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 1561268520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3249227520).

1561268520 is an abundant number, since it is smaller than the sum of its proper divisors (4937186520).

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

1561268520 is a wasteful number, since it uses less digits than its factorization.

1561268520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167 (or 154 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 1561268520 is about 39512.8905548556. The cubic root of 1561268520 is about 1160.0922736744.

The spelling of 1561268520 in words is "one billion, five hundred sixty-one million, two hundred sixty-eight thousand, five hundred twenty".