21406390753905 has 24 divisors (see below), whose sum is σ = 37127300594280. Its totient is φ = 11409698672640.

The previous prime is 21406390753897. The next prime is 21406390753931. The reversal of 21406390753905 is 50935709360412.

21406390753905 is a `hidden beast` number, since 2 + 1 + 40 + 63 + 9 + 0 + 7 + 539 + 0 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 6849044916624 + 14557345837281 = 2617068^2 + 3815409^2 .

It is not a de Polignac number, because 21406390753905 - 2³ = 21406390753897 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 146656720 + ... + 146802609.

It is an arithmetic number, because the mean of its divisors is an integer number (1546970858095).

Almost surely, 2^{21406390753905} is an apocalyptic number.

It is an amenable number.

21406390753905 is a deficient number, since it is larger than the sum of its proper divisors (15720909840375).

21406390753905 is a wasteful number, since it uses less digits than its factorization.

21406390753905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293460961 (or 293460958 counting only the distinct ones).

The product of its (nonzero) digits is 6123600, while the sum is 54.

The spelling of 21406390753905 in words is "twenty-one trillion, four hundred six billion, three hundred ninety million, seven hundred fifty-three thousand, nine hundred five".