1561605020 has 24 divisors (see below), whose sum is σ = 3281308800. Its totient is φ = 624272832.

The previous prime is 1561604983. The next prime is 1561605043. The reversal of 1561605020 is 205061651.

It is a super-2 number, since 2×1561605020² = 4877220476978400800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12986 + ... + 57374.

It is an arithmetic number, because the mean of its divisors is an integer number (136721200).

Almost surely, 2^1561605020 is an apocalyptic number.

1561605020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561605020 is an abundant number, since it is smaller than the sum of its proper divisors (1719703780).

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

1561605020 is a wasteful number, since it uses less digits than its factorization.

1561605020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46157 (or 46155 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 1561605020 is about 39517.1484295110. The cubic root of 1561605020 is about 1160.1756125328.

Adding to 1561605020 its reverse (205061651), we get a palindrome (1766666671).

The spelling of 1561605020 in words is "one billion, five hundred sixty-one million, six hundred five thousand, twenty".