1561516220 has 24 divisors (see below), whose sum is σ = 3577292208. Its totient is φ = 567824000.

The previous prime is 1561516219. The next prime is 1561516259. The reversal of 1561516220 is 226151651.

It is a happy number.

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, 3548681 + ... + 3549120.

It is an arithmetic number, because the mean of its divisors is an integer number (149053842).

Almost surely, 2^1561516220 is an apocalyptic number.

1561516220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561516220 is an abundant number, since it is smaller than the sum of its proper divisors (2015775988).

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

1561516220 is a wasteful number, since it uses less digits than its factorization.

1561516220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7097821 (or 7097819 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 29.

The square root of 1561516220 is about 39516.0248506856. The cubic root of 1561516220 is about 1160.1536211530.

Adding to 1561516220 its reverse (226151651), we get a palindrome (1787667871).

The spelling of 1561516220 in words is "one billion, five hundred sixty-one million, five hundred sixteen thousand, two hundred twenty".