21122211505 has 4 divisors (see below), whose sum is σ = 25346653812. Its totient is φ = 16897769200.

The previous prime is 21122211469. The next prime is 21122211533. The reversal of 21122211505 is 50511222112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15261390369 + 5860821136 = 123537^2 + 76556^2 .

It is not a de Polignac number, because 21122211505 - 2¹³ = 21122203313 is a prime.

It is a super-2 number, since 2×21122211505² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2112221146 + ... + 2112221155.

It is an arithmetic number, because the mean of its divisors is an integer number (6336663453).

Almost surely, 2^21122211505 is an apocalyptic number.

It is an amenable number.

21122211505 is a deficient number, since it is larger than the sum of its proper divisors (4224442307).

21122211505 is an equidigital number, since it uses as much as digits as its factorization.

21122211505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4224442306.

The product of its (nonzero) digits is 400, while the sum is 22.

Adding to 21122211505 its reverse (50511222112), we get a palindrome (71633433617).

The spelling of 21122211505 in words is "twenty-one billion, one hundred twenty-two million, two hundred eleven thousand, five hundred five".