1561555650 has 48 divisors (see below), whose sum is σ = 3877100064. Its totient is φ = 415937280.

The previous prime is 1561555649. The next prime is 1561555651. The reversal of 1561555650 is 565551651.

It is an interprime number because it is at equal distance from previous prime (1561555649) and next prime (1561555651).

It is a junction number, because it is equal to n+sod(n) for n = 1561555599 and 1561555608.

It is not an unprimeable number, because it can be changed into a prime (1561555651) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 136554 + ... + 147546.

It is an arithmetic number, because the mean of its divisors is an integer number (80772918).

Almost surely, 2^1561555650 is an apocalyptic number.

1561555650 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1561555650 is an abundant number, since it is smaller than the sum of its proper divisors (2315544414).

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

1561555650 is a wasteful number, since it uses less digits than its factorization.

1561555650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11955 (or 11950 counting only the distinct ones).

The product of its (nonzero) digits is 112500, while the sum is 39.

The square root of 1561555650 is about 39516.5237590555. The cubic root of 1561555650 is about 1160.1633861219.

The spelling of 1561555650 in words is "one billion, five hundred sixty-one million, five hundred fifty-five thousand, six hundred fifty".