1211639121 has 48 divisors (see below), whose sum is σ = 2277938880. Its totient is φ = 629415360.

The previous prime is 1211639089. The next prime is 1211639131. The reversal of 1211639121 is 1219361121.

It is a happy number.

1211639121 is a `hidden beast` number, since 1 + 2 + 1 + 1 + 639 + 1 + 21 = 666.

It is not a de Polignac number, because 1211639121 - 2⁵ = 1211639089 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1211639131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 27076 + ... + 56181.

It is an arithmetic number, because the mean of its divisors is an integer number (47457060).

Almost surely, 2^1211639121 is an apocalyptic number.

1211639121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1211639121 is a deficient number, since it is larger than the sum of its proper divisors (1066299759).

1211639121 is a wasteful number, since it uses less digits than its factorization.

1211639121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83291 (or 83278 counting only the distinct ones).

The product of its digits is 648, while the sum is 27.

The square root of 1211639121 is about 34808.6069959716. The cubic root of 1211639121 is about 1066.0831907334.

The spelling of 1211639121 in words is "one billion, two hundred eleven million, six hundred thirty-nine thousand, one hundred twenty-one".