1221748817 has 4 divisors (see below), whose sum is σ = 1233610560. Its totient is φ = 1209887076.

The previous prime is 1221748807. The next prime is 1221748831. The reversal of 1221748817 is 7188471221.

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 1221748817 - 2²⁶ = 1154639953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221748807) 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, 5930717 + ... + 5930922.

It is an arithmetic number, because the mean of its divisors is an integer number (308402640).

Almost surely, 2^1221748817 is an apocalyptic number.

It is an amenable number.

1221748817 is a deficient number, since it is larger than the sum of its proper divisors (11861743).

1221748817 is a wasteful number, since it uses less digits than its factorization.

1221748817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11861742.

The product of its digits is 50176, while the sum is 41.

The square root of 1221748817 is about 34953.5236707260. The cubic root of 1221748817 is about 1069.0400500355.

The spelling of 1221748817 in words is "one billion, two hundred twenty-one million, seven hundred forty-eight thousand, eight hundred seventeen".