216649901 has 4 divisors (see below), whose sum is σ = 233315292. Its totient is φ = 199984512.

The previous prime is 216649889. The next prime is 216649919. The reversal of 216649901 is 109946612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 144841225 + 71808676 = 12035^2 + 8474^2 .

It is not a de Polignac number, because 216649901 - 2¹⁴ = 216633517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216649991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8332676 + ... + 8332701.

It is an arithmetic number, because the mean of its divisors is an integer number (58328823).

Almost surely, 2^216649901 is an apocalyptic number.

It is an amenable number.

216649901 is a deficient number, since it is larger than the sum of its proper divisors (16665391).

216649901 is a wasteful number, since it uses less digits than its factorization.

216649901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16665390.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 216649901 is about 14719.0319314825. The cubic root of 216649901 is about 600.6011576665.

The spelling of 216649901 in words is "two hundred sixteen million, six hundred forty-nine thousand, nine hundred one".