100566721 has 2 divisors, whose sum is σ = 100566722. Its totient is φ = 100566720.

The previous prime is 100566691. The next prime is 100566731. The reversal of 100566721 is 127665001.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52403121 + 48163600 = 7239^2 + 6940^2 .

It is an emirp because it is prime and its reverse (127665001) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 100566721 - 2²³ = 92178113 is a prime.

It is a super-2 number, since 2×100566721² = 20227330745383682, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 100566721.

It is not a weakly prime, because it can be changed into another prime (100566731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50283360 + 50283361.

It is an arithmetic number, because the mean of its divisors is an integer number (50283361).

Almost surely, 2^100566721 is an apocalyptic number.

It is an amenable number.

100566721 is a deficient number, since it is larger than the sum of its proper divisors (1).

100566721 is an equidigital number, since it uses as much as digits as its factorization.

100566721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 100566721 is about 10028.2960167717. The cubic root of 100566721 is about 465.0340607879.

The spelling of 100566721 in words is "one hundred million, five hundred sixty-six thousand, seven hundred twenty-one".