1561332720 has 80 divisors (see below), whose sum is σ = 4844689920. Its totient is φ = 415963392.

The previous prime is 1561332673. The next prime is 1561332739. The reversal of 1561332720 is 272331651.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

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 15 ways as a sum of consecutive naturals, for example, 325701 + ... + 330459.

It is an arithmetic number, because the mean of its divisors is an integer number (60558624).

Almost surely, 2^1561332720 is an apocalyptic number.

1561332720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561332720 is an abundant number, since it is smaller than the sum of its proper divisors (3283357200).

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

1561332720 is a wasteful number, since it uses less digits than its factorization.

1561332720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6142 (or 6136 counting only the distinct ones).

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 1561332720 is about 39513.7029396132. The cubic root of 1561332720 is about 1160.1081746127.

The spelling of 1561332720 in words is "one billion, five hundred sixty-one million, three hundred thirty-two thousand, seven hundred twenty".