216426561 has 16 divisors (see below), whose sum is σ = 311498880. Its totient is φ = 132871680.

The previous prime is 216426559. The next prime is 216426563. The reversal of 216426561 is 165624612.

It is an interprime number because it is at equal distance from previous prime (216426559) and next prime (216426563).

It is not a de Polignac number, because 216426561 - 2¹ = 216426559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216426563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10801 + ... + 23441.

It is an arithmetic number, because the mean of its divisors is an integer number (19468680).

Almost surely, 2^216426561 is an apocalyptic number.

It is an amenable number.

216426561 is a deficient number, since it is larger than the sum of its proper divisors (95072319).

216426561 is a wasteful number, since it uses less digits than its factorization.

216426561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13096.

The product of its digits is 17280, while the sum is 33.

The square root of 216426561 is about 14711.4431990883. The cubic root of 216426561 is about 600.3947041796.

It can be divided in two parts, 21642 and 6561, that added together give a triangular number (28203 = T₂₃₇).

The spelling of 216426561 in words is "two hundred sixteen million, four hundred twenty-six thousand, five hundred sixty-one".