21310505 has 32 divisors (see below), whose sum is σ = 27993600. Its totient is φ = 15538432.

The previous prime is 21310493. The next prime is 21310517. The reversal of 21310505 is 50501312.

It is an interprime number because it is at equal distance from previous prime (21310493) and next prime (21310517).

It is not a de Polignac number, because 21310505 - 2¹⁴ = 21294121 is a prime.

It is a zygodrome in base 3.

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, 361166 + ... + 361224.

It is an arithmetic number, because the mean of its divisors is an integer number (874800).

Almost surely, 2^21310505 is an apocalyptic number.

It is an amenable number.

21310505 is a deficient number, since it is larger than the sum of its proper divisors (6683095).

21310505 is a wasteful number, since it uses less digits than its factorization.

21310505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21310505 is about 4616.3302524841. The cubic root of 21310505 is about 277.2455476685.

Adding to 21310505 its reverse (50501312), we get a palindrome (71811817).

The spelling of 21310505 in words is "twenty-one million, three hundred ten thousand, five hundred five".