1221201669 has 4 divisors (see below), whose sum is σ = 1628268896. Its totient is φ = 814134444.

The previous prime is 1221201643. The next prime is 1221201691. The reversal of 1221201669 is 9661021221.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1221201669 - 2⁸ = 1221201413 is a prime.

It is a super-2 number, since 2×1221201669² = 2982667032736771122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221201469) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203533609 + ... + 203533614.

It is an arithmetic number, because the mean of its divisors is an integer number (407067224).

Almost surely, 2^1221201669 is an apocalyptic number.

It is an amenable number.

1221201669 is a deficient number, since it is larger than the sum of its proper divisors (407067227).

1221201669 is an equidigital number, since it uses as much as digits as its factorization.

1221201669 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 407067226.

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 1221201669 is about 34945.6960010814. The cubic root of 1221201669 is about 1068.8804399050.

The spelling of 1221201669 in words is "one billion, two hundred twenty-one million, two hundred one thousand, six hundred sixty-nine".