1216146561 has 16 divisors (see below), whose sum is σ = 1962186624. Its totient is φ = 654061824.

The previous prime is 1216146557. The next prime is 1216146563. The reversal of 1216146561 is 1656416121.

It is not a de Polignac number, because 1216146561 - 2² = 1216146557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216146563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1702930 + ... + 1703643.

It is an arithmetic number, because the mean of its divisors is an integer number (122636664).

Almost surely, 2^1216146561 is an apocalyptic number.

It is an amenable number.

1216146561 is a deficient number, since it is larger than the sum of its proper divisors (746040063).

1216146561 is a wasteful number, since it uses less digits than its factorization.

1216146561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3406600.

The product of its digits is 8640, while the sum is 33.

The square root of 1216146561 is about 34873.2929474691. The cubic root of 1216146561 is about 1067.4035397413.

The spelling of 1216146561 in words is "one billion, two hundred sixteen million, one hundred forty-six thousand, five hundred sixty-one".