1211201001 has 12 divisors (see below), whose sum is σ = 1756168128. Its totient is φ = 804395544.

The previous prime is 1211200993. The next prime is 1211201011. The reversal of 1211201001 is 1001021121.

It is a happy number.

It is not a de Polignac number, because 1211201001 - 2³ = 1211200993 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (1211201011) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 253485 + ... + 258218.

It is an arithmetic number, because the mean of its divisors is an integer number (146347344).

Almost surely, 2^1211201001 is an apocalyptic number.

It is an amenable number.

1211201001 is a deficient number, since it is larger than the sum of its proper divisors (544967127).

1211201001 is a wasteful number, since it uses less digits than its factorization.

1211201001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 511972 (or 511969 counting only the distinct ones).

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

The square root of 1211201001 is about 34802.3131558809. The cubic root of 1211201001 is about 1065.9546792353.

Adding to 1211201001 its reverse (1001021121), we get a palindrome (2212222122).

The spelling of 1211201001 in words is "one billion, two hundred eleven million, two hundred one thousand, one".