1211101020 has 144 divisors (see below), whose sum is σ = 3861617760. Its totient is φ = 306851328.

The previous prime is 1211101019. The next prime is 1211101027. The reversal of 1211101020 is 201011121.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 1211100993 and 1211101011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211101027) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 284266 + ... + 288494.

It is an arithmetic number, because the mean of its divisors is an integer number (26816790).

Almost surely, 2^1211101020 is an apocalyptic number.

1211101020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1211101020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1930808880).

1211101020 is an abundant number, since it is smaller than the sum of its proper divisors (2650516740).

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

1211101020 is a wasteful number, since it uses less digits than its factorization.

1211101020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4324 (or 4319 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 1211101020 is about 34800.8767130945. The cubic root of 1211101020 is about 1065.9253479773.

Adding to 1211101020 its reverse (201011121), we get a palindrome (1412112141).

The spelling of 1211101020 in words is "one billion, two hundred eleven million, one hundred one thousand, twenty".