21162787 has 2 divisors, whose sum is σ = 21162788. Its totient is φ = 21162786.

The previous prime is 21162763. The next prime is 21162793. The reversal of 21162787 is 78726112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21162787 is a prime.

It is not a weakly prime, because it can be changed into another prime (21162727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10581393 + 10581394.

It is an arithmetic number, because the mean of its divisors is an integer number (10581394).

Almost surely, 2^21162787 is an apocalyptic number.

21162787 is a deficient number, since it is larger than the sum of its proper divisors (1).

21162787 is an equidigital number, since it uses as much as digits as its factorization.

21162787 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9408, while the sum is 34.

The square root of 21162787 is about 4600.3029248083. The cubic root of 21162787 is about 276.6034676051.

Adding to 21162787 its reverse (78726112), we get a palindrome (99888899).

The spelling of 21162787 in words is "twenty-one million, one hundred sixty-two thousand, seven hundred eighty-seven".