9781607044021 has 2 divisors, whose sum is σ = 9781607044022. Its totient is φ = 9781607044020.

The previous prime is 9781607044019. The next prime is 9781607044061. The reversal of 9781607044021 is 1204407061879.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9424660541521 + 356946502500 = 3069961^2 + 597450^2 .

It is a cyclic number.

It is not a de Polignac number, because 9781607044021 - 2¹ = 9781607044019 is a prime.

Together with 9781607044019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9781607044061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890803522010 + 4890803522011.

It is an arithmetic number, because the mean of its divisors is an integer number (4890803522011).

Almost surely, 2^{9781607044021} is an apocalyptic number.

It is an amenable number.

9781607044021 is a deficient number, since it is larger than the sum of its proper divisors (1).

9781607044021 is an equidigital number, since it uses as much as digits as its factorization.

9781607044021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 677376, while the sum is 49.

The spelling of 9781607044021 in words is "nine trillion, seven hundred eighty-one billion, six hundred seven million, forty-four thousand, twenty-one".