2001022101 has 24 divisors (see below), whose sum is σ = 3163740216. Its totient is φ = 1211207040.

The previous prime is 2001022099. The next prime is 2001022117. The reversal of 2001022101 is 1012201002.

It can be written as a sum of positive squares in 4 ways, for example, as 62821476 + 1938200625 = 7926^2 + 44025^2 .

It is not a de Polignac number, because 2001022101 - 2¹ = 2001022099 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2001020101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 133050 + ... + 147323.

It is an arithmetic number, because the mean of its divisors is an integer number (131822509).

Almost surely, 2^2001022101 is an apocalyptic number.

It is an amenable number.

2001022101 is a deficient number, since it is larger than the sum of its proper divisors (1162718115).

2001022101 is a wasteful number, since it uses less digits than its factorization.

2001022101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280453 (or 280450 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 2001022101 is about 44732.7855269488. The cubic root of 2001022101 is about 1260.1356411042.

Adding to 2001022101 its reverse (1012201002), we get a palindrome (3013223103).

The spelling of 2001022101 in words is "two billion, one million, twenty-two thousand, one hundred one".