100780021 has 2 divisors, whose sum is σ = 100780022. Its totient is φ = 100780020.

The previous prime is 100780019. The next prime is 100780033. The reversal of 100780021 is 120087001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53363025 + 47416996 = 7305^2 + 6886^2 .

It is an emirp because it is prime and its reverse (120087001) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 100780021 - 2¹ = 100780019 is a prime.

It is a super-2 number, since 2×100780021² = 20313225265520882, which contains 22 as substring.

Together with 100780019, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (100780051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50390010 + 50390011.

It is an arithmetic number, because the mean of its divisors is an integer number (50390011).

Almost surely, 2^100780021 is an apocalyptic number.

It is an amenable number.

100780021 is a deficient number, since it is larger than the sum of its proper divisors (1).

100780021 is an equidigital number, since it uses as much as digits as its factorization.

100780021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 100780021 is about 10038.9252910857. The cubic root of 100780021 is about 465.3626045937.

The spelling of 100780021 in words is "one hundred million, seven hundred eighty thousand, twenty-one".