1211001021 has 6 divisors (see below), whose sum is σ = 1749223710. Its totient is φ = 807334008.

The previous prime is 1211000971. The next prime is 1211001023. The reversal of 1211001021 is 1201001121.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1147176900 + 63824121 = 33870^2 + 7989^2 .

It is not a de Polignac number, because 1211001021 - 2⁷ = 1211000893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 134555669 = 1211001021 / (1 + 2 + 1 + 1 + 0 + 0 + 1 + 0 + 2 + 1).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1211000994 and 1211001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211001023) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 67277826 + ... + 67277843.

It is an arithmetic number, because the mean of its divisors is an integer number (291537285).

Almost surely, 2^1211001021 is an apocalyptic number.

It is an amenable number.

1211001021 is a deficient number, since it is larger than the sum of its proper divisors (538222689).

1211001021 is a wasteful number, since it uses less digits than its factorization.

1211001021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134555675 (or 134555672 counting only the distinct ones).

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

The square root of 1211001021 is about 34799.4399523900. The cubic root of 1211001021 is about 1065.8960098238.

Adding to 1211001021 its reverse (1201001121), we get a palindrome (2412002142).

The spelling of 1211001021 in words is "one billion, two hundred eleven million, one thousand, twenty-one".