1156661551 has 4 divisors (see below), whose sum is σ = 1187922712. Its totient is φ = 1125400392.

The previous prime is 1156661531. The next prime is 1156661557. The reversal of 1156661551 is 1551666511.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1156661551 - 2¹⁹ = 1156137263 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 31261123 = 1156661551 / (1 + 1 + 5 + 6 + 6 + 6 + 1 + 5 + 5 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1156661551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1156661557) 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, 15630525 + ... + 15630598.

It is an arithmetic number, because the mean of its divisors is an integer number (296980678).

Almost surely, 2^1156661551 is an apocalyptic number.

1156661551 is a deficient number, since it is larger than the sum of its proper divisors (31261161).

1156661551 is an equidigital number, since it uses as much as digits as its factorization.

1156661551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31261160.

The product of its digits is 27000, while the sum is 37.

The square root of 1156661551 is about 34009.7272997006. The cubic root of 1156661551 is about 1049.7086269373.

It can be divided in two parts, 115 and 6661551, that added together give a palindrome (6661666).

The spelling of 1156661551 in words is "one billion, one hundred fifty-six million, six hundred sixty-one thousand, five hundred fifty-one".