21516071 has 2 divisors, whose sum is σ = 21516072. Its totient is φ = 21516070.

The previous prime is 21516041. The next prime is 21516119. The reversal of 21516071 is 17061512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21516071 is a prime.

It is a super-2 number, since 2×21516071² = 925882622554082, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21516041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758035 + 10758036.

It is an arithmetic number, because the mean of its divisors is an integer number (10758036).

Almost surely, 2^21516071 is an apocalyptic number.

21516071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21516071 is an equidigital number, since it uses as much as digits as its factorization.

21516071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 420, while the sum is 23.

The square root of 21516071 is about 4638.5419045213. The cubic root of 21516071 is about 278.1341544939.

Adding to 21516071 its reverse (17061512), we get a palindrome (38577583).

The spelling of 21516071 in words is "twenty-one million, five hundred sixteen thousand, seventy-one".