21782071 has 2 divisors, whose sum is σ = 21782072. Its totient is φ = 21782070.

The previous prime is 21782069. The next prime is 21782107. The reversal of 21782071 is 17028712.

Together with next prime (21782107) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21782071 - 2¹ = 21782069 is a prime.

Together with 21782069, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_1376326 and since 21782071 and 1376326 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21782051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10891035 + 10891036.

It is an arithmetic number, because the mean of its divisors is an integer number (10891036).

Almost surely, 2^21782071 is an apocalyptic number.

21782071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21782071 is an equidigital number, since it uses as much as digits as its factorization.

21782071 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 21782071 is about 4667.1266320939. The cubic root of 21782071 is about 279.2756404541.

The spelling of 21782071 in words is "twenty-one million, seven hundred eighty-two thousand, seventy-one".