21211021008 has 30 divisors (see below), whose sum is σ = 59361399474. Its totient is φ = 7070340288.

The previous prime is 21211021003. The next prime is 21211021081. The reversal of 21211021008 is 80012011212.

It can be written as a sum of positive squares in only one way, i.e., 13644108864 + 7566912144 = 116808^2 + 86988^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211021003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 73649235 + ... + 73649522.

Almost surely, 2^21211021008 is an apocalyptic number.

It is an amenable number.

21211021008 is an abundant number, since it is smaller than the sum of its proper divisors (38150378466).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21211021008 is a wasteful number, since it uses less digits than its factorization.

21211021008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147298771 (or 147298762 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

The spelling of 21211021008 in words is "twenty-one billion, two hundred eleven million, twenty-one thousand, eight".