1227920821 has 2 divisors, whose sum is σ = 1227920822. Its totient is φ = 1227920820.

The previous prime is 1227920723. The next prime is 1227920831. The reversal of 1227920821 is 1280297221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1224020196 + 3900625 = 34986^2 + 1975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1227920821 - 2¹³ = 1227912629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1227920831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 613960410 + 613960411.

It is an arithmetic number, because the mean of its divisors is an integer number (613960411).

Almost surely, 2^1227920821 is an apocalyptic number.

It is an amenable number.

1227920821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1227920821 is an equidigital number, since it uses as much as digits as its factorization.

1227920821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 34.

The square root of 1227920821 is about 35041.7011716041. The cubic root of 1227920821 is about 1070.8372115323.

The spelling of 1227920821 in words is "one billion, two hundred twenty-seven million, nine hundred twenty thousand, eight hundred twenty-one".