1561121564 has 12 divisors (see below), whose sum is σ = 2732245488. Its totient is φ = 780480000.

The previous prime is 1561121563. The next prime is 1561121581. The reversal of 1561121564 is 4651211651.

It is a super-4 number, since 4×1561121564⁴ (a number of 38 digits) contains 4444 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1561121564.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561121563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51809 + ... + 76199.

It is an arithmetic number, because the mean of its divisors is an integer number (227687124).

Almost surely, 2^1561121564 is an apocalyptic number.

It is an amenable number.

1561121564 is a deficient number, since it is larger than the sum of its proper divisors (1171123924).

1561121564 is a wasteful number, since it uses less digits than its factorization.

1561121564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40396 (or 40394 counting only the distinct ones).

The product of its digits is 7200, while the sum is 32.

The square root of 1561121564 is about 39511.0309154292. The cubic root of 1561121564 is about 1160.0558742409.

The spelling of 1561121564 in words is "one billion, five hundred sixty-one million, one hundred twenty-one thousand, five hundred sixty-four".