216721529 has 2 divisors, whose sum is σ = 216721530. Its totient is φ = 216721528.

The previous prime is 216721517. The next prime is 216721567. The reversal of 216721529 is 925127612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199515625 + 17205904 = 14125^2 + 4148^2 .

It is a cyclic number.

It is not a de Polignac number, because 216721529 - 2¹² = 216717433 is a prime.

It is a super-2 number, since 2×216721529² = 93936442264195682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (216721129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108360764 + 108360765.

It is an arithmetic number, because the mean of its divisors is an integer number (108360765).

Almost surely, 2^216721529 is an apocalyptic number.

It is an amenable number.

216721529 is a deficient number, since it is larger than the sum of its proper divisors (1).

216721529 is an equidigital number, since it uses as much as digits as its factorization.

216721529 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 35.

The square root of 216721529 is about 14721.4649067272. The cubic root of 216721529 is about 600.6673398947.

The spelling of 216721529 in words is "two hundred sixteen million, seven hundred twenty-one thousand, five hundred twenty-nine".