1281321945 has 24 divisors (see below), whose sum is σ = 2221993800. Its totient is φ = 683053056.

The previous prime is 1281321941. The next prime is 1281321949. The reversal of 1281321945 is 5491231821.

It is an interprime number because it is at equal distance from previous prime (1281321941) and next prime (1281321949).

It can be written as a sum of positive squares in 4 ways, for example, as 41718681 + 1239603264 = 6459^2 + 35208^2 .

It is not a de Polignac number, because 1281321945 - 2² = 1281321941 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1281321941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115711 + ... + 126299.

It is an arithmetic number, because the mean of its divisors is an integer number (92583075).

Almost surely, 2^1281321945 is an apocalyptic number.

1281321945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1281321945 is a deficient number, since it is larger than the sum of its proper divisors (940671855).

1281321945 is a wasteful number, since it uses less digits than its factorization.

1281321945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13289 (or 13286 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 1281321945 is about 35795.5576154360. The cubic root of 1281321945 is about 1086.1407004093.

The spelling of 1281321945 in words is "one billion, two hundred eighty-one million, three hundred twenty-one thousand, nine hundred forty-five".