20216261 has 16 divisors (see below), whose sum is σ = 22362480. Its totient is φ = 18163200.

The previous prime is 20216243. The next prime is 20216263. The reversal of 20216261 is 16261202.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 591361 + 19624900 = 769^2 + 4430^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20216261 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 (20216263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116771 + ... + 116943.

It is an arithmetic number, because the mean of its divisors is an integer number (1397655).

Almost surely, 2^20216261 is an apocalyptic number.

It is an amenable number.

20216261 is a deficient number, since it is larger than the sum of its proper divisors (2146219).

20216261 is a wasteful number, since it uses less digits than its factorization.

20216261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 20216261 is about 4496.2496594384. The cubic root of 20216261 is about 272.4166274136.

Adding to 20216261 its reverse (16261202), we get a palindrome (36477463).

It can be divided in two parts, 20216 and 261, that multiplied together give a triangular number (5276376 = T₃₂₄₈).

The spelling of 20216261 in words is "twenty million, two hundred sixteen thousand, two hundred sixty-one".