1171561621 has 4 divisors (see below), whose sum is σ = 1196488512. Its totient is φ = 1146634732.

The previous prime is 1171561619. The next prime is 1171561631. The reversal of 1171561621 is 1261651711.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1171561621 - 2¹ = 1171561619 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1171561631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12463375 + ... + 12463468.

It is an arithmetic number, because the mean of its divisors is an integer number (299122128).

Almost surely, 2^1171561621 is an apocalyptic number.

It is an amenable number.

1171561621 is a deficient number, since it is larger than the sum of its proper divisors (24926891).

1171561621 is an equidigital number, since it uses as much as digits as its factorization.

1171561621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24926890.

The product of its digits is 2520, while the sum is 31.

The square root of 1171561621 is about 34228.0823447648. The cubic root of 1171561621 is about 1054.1968449074.

The spelling of 1171561621 in words is "one billion, one hundred seventy-one million, five hundred sixty-one thousand, six hundred twenty-one".