1272821509 has 4 divisors (see below), whose sum is σ = 1275845260. Its totient is φ = 1269797760.

The previous prime is 1272821489. The next prime is 1272821519. The reversal of 1272821509 is 9051282721.

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

It can be written as a sum of positive squares in 2 ways, for example, as 72199009 + 1200622500 = 8497^2 + 34650^2 .

It is a cyclic number.

It is not a de Polignac number, because 1272821509 - 2²³ = 1264432901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1272821519) 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, 1511244 + ... + 1512085.

It is an arithmetic number, because the mean of its divisors is an integer number (318961315).

Almost surely, 2^1272821509 is an apocalyptic number.

It is an amenable number.

1272821509 is a deficient number, since it is larger than the sum of its proper divisors (3023751).

1272821509 is an equidigital number, since it uses as much as digits as its factorization.

1272821509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3023750.

The product of its (nonzero) digits is 20160, while the sum is 37.

The square root of 1272821509 is about 35676.6241256092. The cubic root of 1272821509 is about 1083.7335088909.

The spelling of 1272821509 in words is "one billion, two hundred seventy-two million, eight hundred twenty-one thousand, five hundred nine".