21211212085 has 32 divisors (see below), whose sum is σ = 29651311872. Its totient is φ = 14265884160.

The previous prime is 21211212083. The next prime is 21211212107. The reversal of 21211212085 is 58021211212.

It is a happy number.

It is not a de Polignac number, because 21211212085 - 2¹ = 21211212083 is a prime.

It is a super-2 number, since 2×21211212085² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211212083) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 526975 + ... + 565795.

It is an arithmetic number, because the mean of its divisors is an integer number (926603496).

Almost surely, 2^21211212085 is an apocalyptic number.

It is an amenable number.

21211212085 is a deficient number, since it is larger than the sum of its proper divisors (8440099787).

21211212085 is a wasteful number, since it uses less digits than its factorization.

21211212085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39133.

The product of its (nonzero) digits is 640, while the sum is 25.

Adding to 21211212085 its reverse (58021211212), we get a palindrome (79232423297).

The spelling of 21211212085 in words is "twenty-one billion, two hundred eleven million, two hundred twelve thousand, eighty-five".