21011222001 has 64 divisors (see below), whose sum is σ = 35995392000. Its totient is φ = 10806264000.

The previous prime is 21011221997. The next prime is 21011222047. The reversal of 21011222001 is 10022211012.

It is not a de Polignac number, because 21011222001 - 2² = 21011221997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21011222051) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1134030 + ... + 1152408.

It is an arithmetic number, because the mean of its divisors is an integer number (562428000).

Almost surely, 2^21011222001 is an apocalyptic number.

21011222001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21011222001 is a deficient number, since it is larger than the sum of its proper divisors (14984169999).

21011222001 is a wasteful number, since it uses less digits than its factorization.

21011222001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18515 (or 18501 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21011222001 its reverse (10022211012), we get a palindrome (31033433013).

It can be divided in two parts, 210 and 11222001, that added together give a palindrome (11222211).

The spelling of 21011222001 in words is "twenty-one billion, eleven million, two hundred twenty-two thousand, one".