1557121420 has 24 divisors (see below), whose sum is σ = 3273377184. Its totient is φ = 622196736.

The previous prime is 1557121403. The next prime is 1557121427. The reversal of 1557121420 is 241217551.

It is not an unprimeable number, because it can be changed into a prime (1557121427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20917 + ... + 59596.

It is an arithmetic number, because the mean of its divisors is an integer number (136390716).

Almost surely, 2^1557121420 is an apocalyptic number.

1557121420 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1557121420 is an abundant number, since it is smaller than the sum of its proper divisors (1716255764).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1557121420 is a wasteful number, since it uses less digits than its factorization.

1557121420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81489 (or 81487 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 28.

The square root of 1557121420 is about 39460.3778491793. The cubic root of 1557121420 is about 1159.0642026669.

Adding to 1557121420 its reverse (241217551), we get a palindrome (1798338971).

The spelling of 1557121420 in words is "one billion, five hundred fifty-seven million, one hundred twenty-one thousand, four hundred twenty".