21001021210 has 32 divisors (see below), whose sum is σ = 40725214992. Its totient is φ = 7751262720.

The previous prime is 21001021187. The next prime is 21001021219. The reversal of 21001021210 is 1212010012.

It can be written as a sum of positive squares in 8 ways, for example, as 88679889 + 20912341321 = 9417^2 + 144611^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21001021219) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 326862 + ... + 385798.

Almost surely, 2^21001021210 is an apocalyptic number.

21001021210 is a deficient number, since it is larger than the sum of its proper divisors (19724193782).

21001021210 is a wasteful number, since it uses less digits than its factorization.

21001021210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61698.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21001021210 its reverse (1212010012), we get a palindrome (22213031222).

The spelling of 21001021210 in words is "twenty-one billion, one million, twenty-one thousand, two hundred ten".