1221204961 has 4 divisors (see below), whose sum is σ = 1221322432. Its totient is φ = 1221087492.

The previous prime is 1221204947. The next prime is 1221204973. The reversal of 1221204961 is 1694021221.

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 a cyclic number.

It is not a de Polignac number, because 1221204961 - 2⁹ = 1221204449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221204931) 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, 41445 + ... + 64498.

It is an arithmetic number, because the mean of its divisors is an integer number (305330608).

Almost surely, 2^1221204961 is an apocalyptic number.

It is an amenable number.

1221204961 is a deficient number, since it is larger than the sum of its proper divisors (117471).

1221204961 is a wasteful number, since it uses less digits than its factorization.

1221204961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117470.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 1221204961 is about 34945.7431027014. The cubic root of 1221204961 is about 1068.8814003664.

The spelling of 1221204961 in words is "one billion, two hundred twenty-one million, two hundred four thousand, nine hundred sixty-one".