13405821 has 16 divisors (see below), whose sum is σ = 21000000. Its totient is φ = 7499520.

The previous prime is 13405817. The next prime is 13405823. The reversal of 13405821 is 12850431.

It is not a de Polignac number, because 13405821 - 2² = 13405817 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 13405791 and 13405800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13405823) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15196 + ... + 16053.

It is an arithmetic number, because the mean of its divisors is an integer number (1312500).

Almost surely, 2^13405821 is an apocalyptic number.

13405821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13405821 is a deficient number, since it is larger than the sum of its proper divisors (7594179).

13405821 is a wasteful number, since it uses less digits than its factorization.

13405821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31276.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 13405821 is about 3661.3960452265. The cubic root of 13405821 is about 237.5551620716. Note that the first 3 decimals are identical.

The spelling of 13405821 in words is "thirteen million, four hundred five thousand, eight hundred twenty-one".