1221994061 has 4 divisors (see below), whose sum is σ = 1223583900. Its totient is φ = 1220404224.

The previous prime is 1221994049. The next prime is 1221994093. The reversal of 1221994061 is 1604991221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1604991221 = 23 ⋅69782227.

It can be written as a sum of positive squares in 2 ways, for example, as 858138436 + 363855625 = 29294^2 + 19075^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221994061 - 2¹⁴ = 1221977677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221994021) 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, 793766 + ... + 795303.

It is an arithmetic number, because the mean of its divisors is an integer number (305895975).

Almost surely, 2^1221994061 is an apocalyptic number.

It is an amenable number.

1221994061 is a deficient number, since it is larger than the sum of its proper divisors (1589839).

1221994061 is an equidigital number, since it uses as much as digits as its factorization.

1221994061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1589838.

The product of its (nonzero) digits is 7776, while the sum is 35.

The square root of 1221994061 is about 34957.0316388563. The cubic root of 1221994061 is about 1069.1115754080. Note that the first 3 decimals are identical.

The spelling of 1221994061 in words is "one billion, two hundred twenty-one million, nine hundred ninety-four thousand, sixty-one".