1226656721 has 2 divisors, whose sum is σ = 1226656722. Its totient is φ = 1226656720.

The previous prime is 1226656687. The next prime is 1226656727. The reversal of 1226656721 is 1276566221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1174021696 + 52635025 = 34264^2 + 7255^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1226656721 is a prime.

It is a super-2 number, since 2×1226656721² = 3009373422348943682, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1226656727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 613328360 + 613328361.

It is an arithmetic number, because the mean of its divisors is an integer number (613328361).

Almost surely, 2^1226656721 is an apocalyptic number.

It is an amenable number.

1226656721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1226656721 is an equidigital number, since it uses as much as digits as its factorization.

1226656721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60480, while the sum is 38.

The square root of 1226656721 is about 35023.6594461515. The cubic root of 1226656721 is about 1070.4696226586.

The spelling of 1226656721 in words is "one billion, two hundred twenty-six million, six hundred fifty-six thousand, seven hundred twenty-one".