1221246779 has 4 divisors (see below), whose sum is σ = 1241267280. Its totient is φ = 1201226280.

The previous prime is 1221246769. The next prime is 1221246797. The reversal of 1221246779 is 9776421221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9776421221 = 7 ⋅1396631603.

It is a cyclic number.

It is not a de Polignac number, because 1221246779 - 2²⁸ = 952811323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221246739) 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, 10010159 + ... + 10010280.

It is an arithmetic number, because the mean of its divisors is an integer number (310316820).

Almost surely, 2^1221246779 is an apocalyptic number.

1221246779 is a deficient number, since it is larger than the sum of its proper divisors (20020501).

1221246779 is an equidigital number, since it uses as much as digits as its factorization.

1221246779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20020500.

The product of its digits is 84672, while the sum is 41.

The square root of 1221246779 is about 34946.3414251049. The cubic root of 1221246779 is about 1068.8936008770.

The spelling of 1221246779 in words is "one billion, two hundred twenty-one million, two hundred forty-six thousand, seven hundred seventy-nine".