1281721319 has 4 divisors (see below), whose sum is σ = 1323067200. Its totient is φ = 1240375440.

The previous prime is 1281721303. The next prime is 1281721321. The reversal of 1281721319 is 9131271821.

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 1281721319 - 2⁴ = 1281721303 is a prime.

It is a super-2 number, since 2×1281721319² = 3285619079158199522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1281723319) 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, 20672894 + ... + 20672955.

It is an arithmetic number, because the mean of its divisors is an integer number (330766800).

Almost surely, 2^1281721319 is an apocalyptic number.

1281721319 is a deficient number, since it is larger than the sum of its proper divisors (41345881).

1281721319 is an equidigital number, since it uses as much as digits as its factorization.

1281721319 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41345880.

The product of its digits is 6048, while the sum is 35.

The square root of 1281721319 is about 35801.1357222086. The cubic root of 1281721319 is about 1086.2535347358.

The spelling of 1281721319 in words is "one billion, two hundred eighty-one million, seven hundred twenty-one thousand, three hundred nineteen".