2191723965 has 12 divisors (see below), whose sum is σ = 3798988284. Its totient is φ = 1168919424.

The previous prime is 2191723957. The next prime is 2191723973. The reversal of 2191723965 is 5693271912.

It is a happy number.

2191723965 is a `hidden beast` number, since 2 + 191 + 72 + 396 + 5 = 666.

It is an interprime number because it is at equal distance from previous prime (2191723957) and next prime (2191723973).

It can be written as a sum of positive squares in 2 ways, for example, as 1701810009 + 489913956 = 41253^2 + 22134^2 .

It is not a de Polignac number, because 2191723965 - 2³ = 2191723957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 48704977 = 2191723965 / (2 + 1 + 9 + 1 + 7 + 2 + 3 + 9 + 6 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 2191723965.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 24352444 + ... + 24352533.

It is an arithmetic number, because the mean of its divisors is an integer number (316582357).

Almost surely, 2^2191723965 is an apocalyptic number.

It is an amenable number.

2191723965 is a deficient number, since it is larger than the sum of its proper divisors (1607264319).

2191723965 is a wasteful number, since it uses less digits than its factorization.

2191723965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48704988 (or 48704985 counting only the distinct ones).

The product of its digits is 204120, while the sum is 45.

The square root of 2191723965 is about 46815.8516423658. The cubic root of 2191723965 is about 1298.9585277986.

The spelling of 2191723965 in words is "two billion, one hundred ninety-one million, seven hundred twenty-three thousand, nine hundred sixty-five".