1561321950 has 48 divisors (see below), whose sum is σ = 3926641536. Its totient is φ = 410485600.

The previous prime is 1561321919. The next prime is 1561321969. The reversal of 1561321950 is 591231651.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 62652 + ... + 83951.

It is an arithmetic number, because the mean of its divisors is an integer number (81805032).

Almost surely, 2^1561321950 is an apocalyptic number.

1561321950 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1561321950 is an abundant number, since it is smaller than the sum of its proper divisors (2365319586).

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

1561321950 is a wasteful number, since it uses less digits than its factorization.

1561321950 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146689 (or 146684 counting only the distinct ones).

The product of its (nonzero) digits is 8100, while the sum is 33.

The square root of 1561321950 is about 39513.5666575418. The cubic root of 1561321950 is about 1160.1055071493.

The spelling of 1561321950 in words is "one billion, five hundred sixty-one million, three hundred twenty-one thousand, nine hundred fifty".