20505471 has 12 divisors (see below), whose sum is σ = 31804632. Its totient is φ = 11717328.

The previous prime is 20505469. The next prime is 20505473. The reversal of 20505471 is 17450502.

It is an interprime number because it is at equal distance from previous prime (20505469) and next prime (20505473).

It is not a de Polignac number, because 20505471 - 2¹ = 20505469 is a prime.

It is a super-3 number, since 3×20505471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20505473) 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, 69600 + ... + 69893.

It is an arithmetic number, because the mean of its divisors is an integer number (2650386).

Almost surely, 2^20505471 is an apocalyptic number.

20505471 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20505471 is a deficient number, since it is larger than the sum of its proper divisors (11299161).

20505471 is a wasteful number, since it uses less digits than its factorization.

20505471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139510 (or 139503 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 20505471 is about 4528.2966996433. The cubic root of 20505471 is about 273.7095284303.

Adding to 20505471 its reverse (17450502), we get a palindrome (37955973).

The spelling of 20505471 in words is "twenty million, five hundred five thousand, four hundred seventy-one".