155727799621 has 2 divisors, whose sum is σ = 155727799622. Its totient is φ = 155727799620.

The previous prime is 155727799589. The next prime is 155727799637. The reversal of 155727799621 is 126997727551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 94067957025 + 61659842596 = 306705^2 + 248314^2 .

It is a cyclic number.

It is not a de Polignac number, because 155727799621 - 2⁵ = 155727799589 is a prime.

It is a super-2 number, since 2×155727799621² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 155727799621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155727799921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77863899810 + 77863899811.

It is an arithmetic number, because the mean of its divisors is an integer number (77863899811).

Almost surely, 2^155727799621 is an apocalyptic number.

It is an amenable number.

155727799621 is a deficient number, since it is larger than the sum of its proper divisors (1).

155727799621 is an equidigital number, since it uses as much as digits as its factorization.

155727799621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16669800, while the sum is 61.

The spelling of 155727799621 in words is "one hundred fifty-five billion, seven hundred twenty-seven million, seven hundred ninety-nine thousand, six hundred twenty-one".