1561220644 has 12 divisors (see below), whose sum is σ = 2732697100. Its totient is φ = 780450048.

The previous prime is 1561220603. The next prime is 1561220663. The reversal of 1561220644 is 4460221651.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1529748544 + 31472100 = 39112^2 + 5610^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16629 + ... + 58300.

Almost surely, 2^1561220644 is an apocalyptic number.

It is an amenable number.

1561220644 is a deficient number, since it is larger than the sum of its proper divisors (1171476456).

1561220644 is a wasteful number, since it uses less digits than its factorization.

1561220644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80142 (or 80140 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 1561220644 is about 39512.2847226024. The cubic root of 1561220644 is about 1160.0804155508.

The spelling of 1561220644 in words is "one billion, five hundred sixty-one million, two hundred twenty thousand, six hundred forty-four".