100642781 has 2 divisors, whose sum is σ = 100642782. Its totient is φ = 100642780.

The previous prime is 100642757. The next prime is 100642783. The reversal of 100642781 is 187246001.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 85858756 + 14784025 = 9266^2 + 3845^2 .

It is a cyclic number.

It is not a de Polignac number, because 100642781 - 2²² = 96448477 is a prime.

It is a super-2 number, since 2×100642781² = 20257938734827922, which contains 22 as substring.

Together with 100642783, 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 (100642783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50321390 + 50321391.

It is an arithmetic number, because the mean of its divisors is an integer number (50321391).

Almost surely, 2^100642781 is an apocalyptic number.

It is an amenable number.

100642781 is a deficient number, since it is larger than the sum of its proper divisors (1).

100642781 is an equidigital number, since it uses as much as digits as its factorization.

100642781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 100642781 is about 10032.0875693945. The cubic root of 100642781 is about 465.1512684718.

Adding to 100642781 its reverse (187246001), we get a palindrome (287888782).

The spelling of 100642781 in words is "one hundred million, six hundred forty-two thousand, seven hundred eighty-one".