1287423821 has 8 divisors (see below), whose sum is σ = 1396403064. Its totient is φ = 1182138880.

The previous prime is 1287423817. The next prime is 1287423833. The reversal of 1287423821 is 1283247821.

It can be written as a sum of positive squares in 4 ways, for example, as 6786025 + 1280637796 = 2605^2 + 35786^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1287423821 - 2² = 1287423817 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 (1287423811) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 922850 + ... + 924243.

It is an arithmetic number, because the mean of its divisors is an integer number (174550383).

Almost surely, 2^1287423821 is an apocalyptic number.

It is an amenable number.

1287423821 is a deficient number, since it is larger than the sum of its proper divisors (108979243).

1287423821 is a wasteful number, since it uses less digits than its factorization.

1287423821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1847151.

The product of its digits is 43008, while the sum is 38.

The square root of 1287423821 is about 35880.6886918298. The cubic root of 1287423821 is about 1087.8621005143.

The spelling of 1287423821 in words is "one billion, two hundred eighty-seven million, four hundred twenty-three thousand, eight hundred twenty-one".