1657887421 has 2 divisors, whose sum is σ = 1657887422. Its totient is φ = 1657887420.

The previous prime is 1657887397. The next prime is 1657887499. The reversal of 1657887421 is 1247887561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 865183396 + 792704025 = 29414^2 + 28155^2 .

It is a cyclic number.

It is not a de Polignac number, because 1657887421 - 2⁷ = 1657887293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1657827421) 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 as a sum of consecutive naturals, namely, 828943710 + 828943711.

It is an arithmetic number, because the mean of its divisors is an integer number (828943711).

Almost surely, 2^1657887421 is an apocalyptic number.

It is an amenable number.

1657887421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1657887421 is an equidigital number, since it uses as much as digits as its factorization.

1657887421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 752640, while the sum is 49.

The square root of 1657887421 is about 40717.1637150723. The cubic root of 1657887421 is about 1183.5456461120.

The spelling of 1657887421 in words is "one billion, six hundred fifty-seven million, eight hundred eighty-seven thousand, four hundred twenty-one".