21816407 has 2 divisors, whose sum is σ = 21816408. Its totient is φ = 21816406.

The previous prime is 21816373. The next prime is 21816451. The reversal of 21816407 is 70461812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21816407 is a prime.

It is a super-2 number, since 2×21816407² = 951911228779298, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21816407.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21816107) 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 as a sum of consecutive naturals, namely, 10908203 + 10908204.

It is an arithmetic number, because the mean of its divisors is an integer number (10908204).

Almost surely, 2^21816407 is an apocalyptic number.

21816407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21816407 is an equidigital number, since it uses as much as digits as its factorization.

21816407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21816407 is about 4670.8036781693. The cubic root of 21816407 is about 279.4223080838.

The spelling of 21816407 in words is "twenty-one million, eight hundred sixteen thousand, four hundred seven".