1438779821 has 2 divisors, whose sum is σ = 1438779822. Its totient is φ = 1438779820.

The previous prime is 1438779787. The next prime is 1438780087. The reversal of 1438779821 is 1289778341.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1374555625 + 64224196 = 37075^2 + 8014^2 .

It is a cyclic number.

It is not a de Polignac number, because 1438779821 - 2¹⁰ = 1438778797 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1438779821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1438778821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 719389910 + 719389911.

It is an arithmetic number, because the mean of its divisors is an integer number (719389911).

Almost surely, 2^1438779821 is an apocalyptic number.

It is an amenable number.

1438779821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1438779821 is an equidigital number, since it uses as much as digits as its factorization.

1438779821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 677376, while the sum is 50.

The square root of 1438779821 is about 37931.2512448509. The cubic root of 1438779821 is about 1128.9241910821.

The spelling of 1438779821 in words is "one billion, four hundred thirty-eight million, seven hundred seventy-nine thousand, eight hundred twenty-one".