216521476 has 6 divisors (see below), whose sum is σ = 378912590. Its totient is φ = 108260736.

The previous prime is 216521449. The next prime is 216521507. The reversal of 216521476 is 674125612.

It can be written as a sum of positive squares in only one way, i.e., 167184900 + 49336576 = 12930^2 + 7024^2 .

It is an alternating number because its digits alternate between even and odd.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27065181 + ... + 27065188.

Almost surely, 2^216521476 is an apocalyptic number.

It is an amenable number.

216521476 is a deficient number, since it is larger than the sum of its proper divisors (162391114).

216521476 is a wasteful number, since it uses less digits than its factorization.

216521476 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54130373 (or 54130371 counting only the distinct ones).

The product of its digits is 20160, while the sum is 34.

The square root of 216521476 is about 14714.6687356529. The cubic root of 216521476 is about 600.4824600979.

The spelling of 216521476 in words is "two hundred sixteen million, five hundred twenty-one thousand, four hundred seventy-six".