1561661216072 has 16 divisors (see below), whose sum is σ = 2930192952300. Its totient is φ = 780276428800.

The previous prime is 1561661215999. The next prime is 1561661216107. The reversal of 1561661216072 is 2706121661651.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 984052096036 + 577609120036 = 991994^2 + 760006^2 .

It is a super-2 number, since 2×1561661216072² (a number of 25 digits) contains 22 as substring.

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, 69260429 + ... + 69282972.

Almost surely, 2^{1561661216072} is an apocalyptic number.

It is an amenable number.

1561661216072 is a deficient number, since it is larger than the sum of its proper divisors (1368531736228).

1561661216072 is a wasteful number, since it uses less digits than its factorization.

1561661216072 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138544816 (or 138544812 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 44.

The spelling of 1561661216072 in words is "one trillion, five hundred sixty-one billion, six hundred sixty-one million, two hundred sixteen thousand, seventy-two".