1221211836 has 48 divisors (see below), whose sum is σ = 3409655200. Its totient is φ = 375757056.

The previous prime is 1221211801. The next prime is 1221211867. The reversal of 1221211836 is 6381121221.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 433501 + ... + 436308.

Almost surely, 2^1221211836 is an apocalyptic number.

It is an amenable number.

1221211836 is an abundant number, since it is smaller than the sum of its proper divisors (2188443364).

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

1221211836 is a wasteful number, since it uses less digits than its factorization.

1221211836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869835 (or 869827 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 1221211836 is about 34945.8414693365. The cubic root of 1221211836 is about 1068.8834061847.

The spelling of 1221211836 in words is "one billion, two hundred twenty-one million, two hundred eleven thousand, eight hundred thirty-six".