216621403 has 4 divisors (see below), whose sum is σ = 217162008. Its totient is φ = 216080800.

The previous prime is 216621373. The next prime is 216621407. The reversal of 216621403 is 304126612.

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

It is a cyclic number.

It is not a de Polignac number, because 216621403 - 2⁹ = 216620891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216621407) 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, 269701 + ... + 270502.

It is an arithmetic number, because the mean of its divisors is an integer number (54290502).

Almost surely, 2^216621403 is an apocalyptic number.

216621403 is a deficient number, since it is larger than the sum of its proper divisors (540605).

216621403 is an equidigital number, since it uses as much as digits as its factorization.

216621403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540604.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 216621403 is about 14718.0638332629. The cubic root of 216621403 is about 600.5748222712.

The spelling of 216621403 in words is "two hundred sixteen million, six hundred twenty-one thousand, four hundred three".