216181556 has 6 divisors (see below), whose sum is σ = 378317730. Its totient is φ = 108090776.

The previous prime is 216181549. The next prime is 216181583. The reversal of 216181556 is 655181612.

It is a happy number.

216181556 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 119159056 + 97022500 = 10916^2 + 9850^2 .

It is a super-2 number, since 2×216181556² = 93468930309162272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27022691 + ... + 27022698.

It is an arithmetic number, because the mean of its divisors is an integer number (63052955).

Almost surely, 2^216181556 is an apocalyptic number.

It is an amenable number.

216181556 is a deficient number, since it is larger than the sum of its proper divisors (162136174).

216181556 is a wasteful number, since it uses less digits than its factorization.

216181556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54045393 (or 54045391 counting only the distinct ones).

The product of its digits is 14400, while the sum is 35.

The square root of 216181556 is about 14703.1138198682. The cubic root of 216181556 is about 600.1680603292.

The spelling of 216181556 in words is "two hundred sixteen million, one hundred eighty-one thousand, five hundred fifty-six".