90668721 has 16 divisors (see below), whose sum is σ = 142027200. Its totient is φ = 50723520.

The previous prime is 90668717. The next prime is 90668723. The reversal of 90668721 is 12786609.

It is not a de Polignac number, because 90668721 - 2² = 90668717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 90668721.

It is not an unprimeable number, because it can be changed into a prime (90668723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 105246 + ... + 106103.

It is an arithmetic number, because the mean of its divisors is an integer number (8876700).

Almost surely, 2^90668721 is an apocalyptic number.

It is an amenable number.

90668721 is a deficient number, since it is larger than the sum of its proper divisors (51358479).

90668721 is a wasteful number, since it uses less digits than its factorization.

90668721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211376.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 90668721 is about 9522.0124448564. The cubic root of 90668721 is about 449.2476663669.

The spelling of 90668721 in words is "ninety million, six hundred sixty-eight thousand, seven hundred twenty-one".