1601891515621 has 2 divisors, whose sum is σ = 1601891515622. Its totient is φ = 1601891515620.

The previous prime is 1601891515591. The next prime is 1601891515639. The reversal of 1601891515621 is 1265151981061.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1446114477025 + 155777038596 = 1202545^2 + 394686^2 .

It is a cyclic number.

It is not a de Polignac number, because 1601891515621 - 2¹³ = 1601891507429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1601891515681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 800945757810 + 800945757811.

It is an arithmetic number, because the mean of its divisors is an integer number (800945757811).

Almost surely, 2^{1601891515621} is an apocalyptic number.

It is an amenable number.

1601891515621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1601891515621 is an equidigital number, since it uses as much as digits as its factorization.

1601891515621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 129600, while the sum is 46.

The spelling of 1601891515621 in words is "one trillion, six hundred one billion, eight hundred ninety-one million, five hundred fifteen thousand, six hundred twenty-one".