1438685821 has 4 divisors (see below), whose sum is σ = 1445023872. Its totient is φ = 1432347772.

The previous prime is 1438685803. The next prime is 1438685849. The reversal of 1438685821 is 1285868341.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1285868341 = 2939 ⋅437519.

It is a cyclic number.

It is not a de Polignac number, because 1438685821 - 2¹³ = 1438677629 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 (1438685021) 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, 3168685 + ... + 3169138.

It is an arithmetic number, because the mean of its divisors is an integer number (361255968).

Almost surely, 2^1438685821 is an apocalyptic number.

It is an amenable number.

1438685821 is a deficient number, since it is larger than the sum of its proper divisors (6338051).

1438685821 is an equidigital number, since it uses as much as digits as its factorization.

1438685821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6338050.

The product of its digits is 368640, while the sum is 46.

The square root of 1438685821 is about 37930.0121407837. The cubic root of 1438685821 is about 1128.8996051602.

The spelling of 1438685821 in words is "one billion, four hundred thirty-eight million, six hundred eighty-five thousand, eight hundred twenty-one".