21478166505 has 24 divisors (see below), whose sum is σ = 37232467272. Its totient is φ = 11453900544.

The previous prime is 21478166497. The next prime is 21478166531. The reversal of 21478166505 is 50566187412.

21478166505 is a `hidden beast` number, since 2 + 1 + 4 + 7 + 81 + 66 + 505 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 2143296 + 21476023209 = 1464^2 + 146547^2 .

It is not a de Polignac number, because 21478166505 - 2³ = 21478166497 is a prime.

It is a super-2 number, since 2×21478166505² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 662637 + ... + 694293.

It is an arithmetic number, because the mean of its divisors is an integer number (1551352803).

Almost surely, 2^21478166505 is an apocalyptic number.

It is an amenable number.

21478166505 is a deficient number, since it is larger than the sum of its proper divisors (15754300767).

21478166505 is a wasteful number, since it uses less digits than its factorization.

21478166505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46745 (or 46742 counting only the distinct ones).

The product of its (nonzero) digits is 403200, while the sum is 45.

The spelling of 21478166505 in words is "twenty-one billion, four hundred seventy-eight million, one hundred sixty-six thousand, five hundred five".