221000100781 has 2 divisors, whose sum is σ = 221000100782. Its totient is φ = 221000100780.

The previous prime is 221000100751. The next prime is 221000100791. The reversal of 221000100781 is 187001000122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 194344314025 + 26655786756 = 440845^2 + 163266^2 .

It is a cyclic number.

It is not a de Polignac number, because 221000100781 - 2¹³ = 221000092589 is a prime.

It is a super-2 number, since 2×221000100781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221000100701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110500050390 + 110500050391.

It is an arithmetic number, because the mean of its divisors is an integer number (110500050391).

Almost surely, 2^221000100781 is an apocalyptic number.

It is an amenable number.

221000100781 is a deficient number, since it is larger than the sum of its proper divisors (1).

221000100781 is an equidigital number, since it uses as much as digits as its factorization.

221000100781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 224, while the sum is 22.

The spelling of 221000100781 in words is "two hundred twenty-one billion, one hundred thousand, seven hundred eighty-one".