1405991 has 4 divisors (see below), whose sum is σ = 1419000. Its totient is φ = 1392984.

The previous prime is 1405979. The next prime is 1405997. The reversal of 1405991 is 1995041.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1995041 = 193 ⋅10337.

It is a cyclic number.

It is not a de Polignac number, because 1405991 - 2⁶ = 1405927 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 (1405997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6341 + ... + 6558.

It is an arithmetic number, because the mean of its divisors is an integer number (354750).

2^1405991 is an apocalyptic number.

1405991 is a deficient number, since it is larger than the sum of its proper divisors (13009).

1405991 is a wasteful number, since it uses less digits than its factorization.

1405991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13008.

The product of its (nonzero) digits is 1620, while the sum is 29.

The square root of 1405991 is about 1185.7449135459. The cubic root of 1405991 is about 112.0282401152.

The spelling of 1405991 in words is "one million, four hundred five thousand, nine hundred ninety-one".