1216756421 has 2 divisors, whose sum is σ = 1216756422. Its totient is φ = 1216756420.

The previous prime is 1216756403. The next prime is 1216756439. The reversal of 1216756421 is 1246576121.

It is a balanced prime because it is at equal distance from previous prime (1216756403) and next prime (1216756439).

It can be written as a sum of positive squares in only one way, i.e., 1184323396 + 32433025 = 34414^2 + 5695^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216756421 - 2⁶ = 1216756357 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1216750421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608378210 + 608378211.

It is an arithmetic number, because the mean of its divisors is an integer number (608378211).

Almost surely, 2^1216756421 is an apocalyptic number.

It is an amenable number.

1216756421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216756421 is an equidigital number, since it uses as much as digits as its factorization.

1216756421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 35.

The square root of 1216756421 is about 34882.0357920807. The cubic root of 1216756421 is about 1067.5819332455.

The spelling of 1216756421 in words is "one billion, two hundred sixteen million, seven hundred fifty-six thousand, four hundred twenty-one".