1555142021 has 2 divisors, whose sum is σ = 1555142022. Its totient is φ = 1555142020.

The previous prime is 1555141967. The next prime is 1555142027. The reversal of 1555142021 is 1202415551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1435348996 + 119793025 = 37886^2 + 10945^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1555142021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1555142027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 777571010 + 777571011.

It is an arithmetic number, because the mean of its divisors is an integer number (777571011).

Almost surely, 2^1555142021 is an apocalyptic number.

It is an amenable number.

1555142021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1555142021 is an equidigital number, since it uses as much as digits as its factorization.

1555142021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2000, while the sum is 26.

The square root of 1555142021 is about 39435.2890315261. The cubic root of 1555142021 is about 1158.5728636860.

Adding to 1555142021 its reverse (1202415551), we get a palindrome (2757557572).

The spelling of 1555142021 in words is "one billion, five hundred fifty-five million, one hundred forty-two thousand, twenty-one".