1221328906 has 16 divisors (see below), whose sum is σ = 2102855040. Its totient is φ = 521139600.

The previous prime is 1221328903. The next prime is 1221328919. The reversal of 1221328906 is 6098231221.

It is not an unprimeable number, because it can be changed into a prime (1221328903) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187270 + ... + 193681.

It is an arithmetic number, because the mean of its divisors is an integer number (131428440).

Almost surely, 2^1221328906 is an apocalyptic number.

1221328906 is a deficient number, since it is larger than the sum of its proper divisors (881526134).

1221328906 is a wasteful number, since it uses less digits than its factorization.

1221328906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381189.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 1221328906 is about 34947.5164496706. The cubic root of 1221328906 is about 1068.9175608330.

The spelling of 1221328906 in words is "one billion, two hundred twenty-one million, three hundred twenty-eight thousand, nine hundred six".