918906721 has 2 divisors, whose sum is σ = 918906722. Its totient is φ = 918906720.

The previous prime is 918906701. The next prime is 918906817. The reversal of 918906721 is 127609819.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 508277025 + 410629696 = 22545^2 + 20264^2 .

It is a cyclic number.

It is not a de Polignac number, because 918906721 - 2¹¹ = 918904673 is a prime.

It is equal to p_46926448 and since 918906721 and 46926448 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (918906701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 459453360 + 459453361.

It is an arithmetic number, because the mean of its divisors is an integer number (459453361).

Almost surely, 2^918906721 is an apocalyptic number.

It is an amenable number.

918906721 is a deficient number, since it is larger than the sum of its proper divisors (1).

918906721 is an equidigital number, since it uses as much as digits as its factorization.

918906721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 43.

The square root of 918906721 is about 30313.4742482613. The cubic root of 918906721 is about 972.2034159248.

The spelling of 918906721 in words is "nine hundred eighteen million, nine hundred six thousand, seven hundred twenty-one".