1231977509 has 4 divisors (see below), whose sum is σ = 1407974304. Its totient is φ = 1055980716.

The previous prime is 1231977491. The next prime is 1231977517. The reversal of 1231977509 is 9057791321.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9057791321 = 19 ⋅476725859.

It is not a de Polignac number, because 1231977509 - 2²⁸ = 963542053 is a prime.

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 1231977509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231977599) 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, 87998387 + ... + 87998400.

It is an arithmetic number, because the mean of its divisors is an integer number (351993576).

Almost surely, 2^1231977509 is an apocalyptic number.

It is an amenable number.

1231977509 is a deficient number, since it is larger than the sum of its proper divisors (175996795).

1231977509 is an equidigital number, since it uses as much as digits as its factorization.

1231977509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175996794.

The product of its (nonzero) digits is 119070, while the sum is 44.

The square root of 1231977509 is about 35099.5371621906. The cubic root of 1231977509 is about 1072.0151586578.

The spelling of 1231977509 in words is "one billion, two hundred thirty-one million, nine hundred seventy-seven thousand, five hundred nine".