100638721 has 2 divisors, whose sum is σ = 100638722. Its totient is φ = 100638720.

The previous prime is 100638697. The next prime is 100638767. The reversal of 100638721 is 127836001.

It is the 4096-th star number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 92910321 + 7728400 = 9639^2 + 2780^2 .

It is a cyclic number.

It is not a de Polignac number, because 100638721 - 2¹³ = 100630529 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 100638721.

It is not a weakly prime, because it can be changed into another prime (100638781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50319360 + 50319361.

It is an arithmetic number, because the mean of its divisors is an integer number (50319361).

Almost surely, 2^100638721 is an apocalyptic number.

It is an amenable number.

100638721 is a deficient number, since it is larger than the sum of its proper divisors (1).

100638721 is an equidigital number, since it uses as much as digits as its factorization.

100638721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 100638721 is about 10031.8852166480. The cubic root of 100638721 is about 465.1450135455.

The spelling of 100638721 in words is "one hundred million, six hundred thirty-eight thousand, seven hundred twenty-one".