1657342121 has 4 divisors (see below), whose sum is σ = 1754832852. Its totient is φ = 1559851392.

The previous prime is 1657342117. The next prime is 1657342129. The reversal of 1657342121 is 1212437561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1212437561 = 67 ⋅18096083.

It can be written as a sum of positive squares in 2 ways, for example, as 1388382121 + 268960000 = 37261^2 + 16400^2 .

It is a cyclic number.

It is not a de Polignac number, because 1657342121 - 2² = 1657342117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1657342129) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48745340 + ... + 48745373.

It is an arithmetic number, because the mean of its divisors is an integer number (438708213).

Almost surely, 2^1657342121 is an apocalyptic number.

It is an amenable number.

1657342121 is a deficient number, since it is larger than the sum of its proper divisors (97490731).

1657342121 is an equidigital number, since it uses as much as digits as its factorization.

1657342121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97490730.

The product of its digits is 10080, while the sum is 32.

The square root of 1657342121 is about 40710.4669710383. The cubic root of 1657342121 is about 1183.4158708723.

Adding to 1657342121 its reverse (1212437561), we get a palindrome (2869779682).

The spelling of 1657342121 in words is "one billion, six hundred fifty-seven million, three hundred forty-two thousand, one hundred twenty-one".