1281623621 has 2 divisors, whose sum is σ = 1281623622. Its totient is φ = 1281623620.

The previous prime is 1281623611. The next prime is 1281623653. The reversal of 1281623621 is 1263261821.

It is an a-pointer prime, because the next prime (1281623653) can be obtained adding 1281623621 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 779191396 + 502432225 = 27914^2 + 22415^2 .

It is a cyclic number.

It is not a de Polignac number, because 1281623621 - 2¹⁰ = 1281622597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1281623611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 640811810 + 640811811.

It is an arithmetic number, because the mean of its divisors is an integer number (640811811).

Almost surely, 2^1281623621 is an apocalyptic number.

It is an amenable number.

1281623621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1281623621 is an equidigital number, since it uses as much as digits as its factorization.

1281623621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 32.

The square root of 1281623621 is about 35799.7712422859. The cubic root of 1281623621 is about 1086.2259344838.

The spelling of 1281623621 in words is "one billion, two hundred eighty-one million, six hundred twenty-three thousand, six hundred twenty-one".