21616187 has 2 divisors, whose sum is σ = 21616188. Its totient is φ = 21616186.

The previous prime is 21616171. The next prime is 21616201. The reversal of 21616187 is 78161612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21616187 - 2⁴ = 21616171 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21616157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808093 + 10808094.

It is an arithmetic number, because the mean of its divisors is an integer number (10808094).

Almost surely, 2^21616187 is an apocalyptic number.

21616187 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616187 is an equidigital number, since it uses as much as digits as its factorization.

21616187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 32.

The square root of 21616187 is about 4649.3211332409. The cubic root of 21616187 is about 278.5648806075.

Adding to 21616187 its reverse (78161612), we get a palindrome (99777799).

The spelling of 21616187 in words is "twenty-one million, six hundred sixteen thousand, one hundred eighty-seven".