21105657477 has 12 divisors (see below), whose sum is σ = 30489249804. Its totient is φ = 14068915200.

The previous prime is 21105657457. The next prime is 21105657487. The reversal of 21105657477 is 77475650112.

21105657477 is a `hidden beast` number, since 2 + 1 + 1 + 0 + 5 + 6 + 574 + 77 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 8525567556 + 12580089921 = 92334^2 + 112161^2 .

It is not a de Polignac number, because 21105657477 - 2¹¹ = 21105655429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105657457) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 35718 + ... + 208535.

It is an arithmetic number, because the mean of its divisors is an integer number (2540770817).

Almost surely, 2^21105657477 is an apocalyptic number.

It is an amenable number.

21105657477 is a deficient number, since it is larger than the sum of its proper divisors (9383592327).

21105657477 is a wasteful number, since it uses less digits than its factorization.

21105657477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253860 (or 253857 counting only the distinct ones).

The product of its (nonzero) digits is 411600, while the sum is 45.

The spelling of 21105657477 in words is "twenty-one billion, one hundred five million, six hundred fifty-seven thousand, four hundred seventy-seven".