1231005405 has 64 divisors (see below), whose sum is σ = 2297438208. Its totient is φ = 551232000.

The previous prime is 1231005403. The next prime is 1231005407. The reversal of 1231005405 is 5045001321.

It is an interprime number because it is at equal distance from previous prime (1231005403) and next prime (1231005407).

It is not a de Polignac number, because 1231005405 - 2¹ = 1231005403 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231005403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1638780 + ... + 1639530.

It is an arithmetic number, because the mean of its divisors is an integer number (35897472).

Almost surely, 2^1231005405 is an apocalyptic number.

1231005405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1231005405 is a deficient number, since it is larger than the sum of its proper divisors (1066432803).

1231005405 is a wasteful number, since it uses less digits than its factorization.

1231005405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1066.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 1231005405 is about 35085.6866114944. The cubic root of 1231005405 is about 1071.7331230870.

Adding to 1231005405 its reverse (5045001321), we get a palindrome (6276006726).

The spelling of 1231005405 in words is "one billion, two hundred thirty-one million, five thousand, four hundred five".