21012220133 has 4 divisors (see below), whose sum is σ = 22248233100. Its totient is φ = 19776207168.

The previous prime is 21012220127. The next prime is 21012220153. The reversal of 21012220133 is 33102221012.

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 19270159489 + 1742060644 = 138817^2 + 41738^2 .

It is not a de Polignac number, because 21012220133 - 2¹² = 21012216037 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 1236012949 = 21012220133 / (2 + 1 + 0 + 1 + 2 + 2 + 2 + 0 + 1 + 3 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012220153) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 618006458 + ... + 618006491.

It is an arithmetic number, because the mean of its divisors is an integer number (5562058275).

Almost surely, 2^21012220133 is an apocalyptic number.

It is an amenable number.

21012220133 is a deficient number, since it is larger than the sum of its proper divisors (1236012967).

21012220133 is a wasteful number, since it uses less digits than its factorization.

21012220133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1236012966.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21012220133 its reverse (33102221012), we get a palindrome (54114441145).

The spelling of 21012220133 in words is "twenty-one billion, twelve million, two hundred twenty thousand, one hundred thirty-three".