1138721 has 4 divisors (see below), whose sum is σ = 1146132. Its totient is φ = 1131312.

The previous prime is 1138717. The next prime is 1138729. The reversal of 1138721 is 1278311.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1278311 = 283 ⋅4517.

It can be written as a sum of positive squares in 2 ways, for example, as 583696 + 555025 = 764^2 + 745^2 .

It is a cyclic number.

It is not a de Polignac number, because 1138721 - 2² = 1138717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1138729) 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, 3470 + ... + 3783.

It is an arithmetic number, because the mean of its divisors is an integer number (286533).

2^1138721 is an apocalyptic number.

It is an amenable number.

1138721 is a deficient number, since it is larger than the sum of its proper divisors (7411).

1138721 is an equidigital number, since it uses as much as digits as its factorization.

1138721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7410.

The product of its digits is 336, while the sum is 23.

The square root of 1138721 is about 1067.1087104883. The cubic root of 1138721 is about 104.4253108236.

The spelling of 1138721 in words is "one million, one hundred thirty-eight thousand, seven hundred twenty-one".