1551061021 has 2 divisors, whose sum is σ = 1551061022. Its totient is φ = 1551061020.

The previous prime is 1551061013. The next prime is 1551061063. The reversal of 1551061021 is 1201601551.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1325760921 + 225300100 = 36411^2 + 15010^2 .

It is a cyclic number.

It is not a de Polignac number, because 1551061021 - 2³ = 1551061013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1551060983 and 1551061001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1551061121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775530510 + 775530511.

It is an arithmetic number, because the mean of its divisors is an integer number (775530511).

Almost surely, 2^1551061021 is an apocalyptic number.

It is an amenable number.

1551061021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551061021 is an equidigital number, since it uses as much as digits as its factorization.

1551061021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 22.

The square root of 1551061021 is about 39383.5120450170. The cubic root of 1551061021 is about 1157.5585345150.

Adding to 1551061021 its reverse (1201601551), we get a palindrome (2752662572).

The spelling of 1551061021 in words is "one billion, five hundred fifty-one million, sixty-one thousand, twenty-one".