20405216505 has 32 divisors (see below), whose sum is σ = 33371035776. Its totient is φ = 10643203584.

The previous prime is 20405216483. The next prime is 20405216527. The reversal of 20405216505 is 50561250402.

It is an interprime number because it is at equal distance from previous prime (20405216483) and next prime (20405216527).

It is not a de Polignac number, because 20405216505 - 2¹² = 20405212409 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 207834 + ... + 289836.

It is an arithmetic number, because the mean of its divisors is an integer number (1042844868).

Almost surely, 2^20405216505 is an apocalyptic number.

It is an amenable number.

20405216505 is a deficient number, since it is larger than the sum of its proper divisors (12965819271).

20405216505 is a wasteful number, since it uses less digits than its factorization.

20405216505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82377.

The product of its (nonzero) digits is 12000, while the sum is 30.

Adding to 20405216505 its reverse (50561250402), we get a palindrome (70966466907).

The spelling of 20405216505 in words is "twenty billion, four hundred five million, two hundred sixteen thousand, five hundred five".