1155661621 has 2 divisors, whose sum is σ = 1155661622. Its totient is φ = 1155661620.

The previous prime is 1155661609. The next prime is 1155661693. The reversal of 1155661621 is 1261665511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 979064100 + 176597521 = 31290^2 + 13289^2 .

It is a cyclic number.

It is not a de Polignac number, because 1155661621 - 2⁹ = 1155661109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1155661021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 577830810 + 577830811.

It is an arithmetic number, because the mean of its divisors is an integer number (577830811).

Almost surely, 2^1155661621 is an apocalyptic number.

It is an amenable number.

1155661621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1155661621 is an equidigital number, since it uses as much as digits as its factorization.

1155661621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10800, while the sum is 34.

The square root of 1155661621 is about 33995.0234740322. The cubic root of 1155661621 is about 1049.4060498754.

The spelling of 1155661621 in words is "one billion, one hundred fifty-five million, six hundred sixty-one thousand, six hundred twenty-one".