1642656121 has 4 divisors (see below), whose sum is σ = 1642836112. Its totient is φ = 1642476132.

The previous prime is 1642656101. The next prime is 1642656131. The reversal of 1642656121 is 1216562461.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1216562461 = 547 ⋅2224063.

It is a cyclic number.

It is not a de Polignac number, because 1642656121 - 2⁵ = 1642656089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1642656101) 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 3 ways as a sum of consecutive naturals, for example, 75531 + ... + 94816.

It is an arithmetic number, because the mean of its divisors is an integer number (410709028).

Almost surely, 2^1642656121 is an apocalyptic number.

It is an amenable number.

1642656121 is a deficient number, since it is larger than the sum of its proper divisors (179991).

1642656121 is an equidigital number, since it uses as much as digits as its factorization.

1642656121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179990.

The product of its digits is 17280, while the sum is 34.

The square root of 1642656121 is about 40529.6943117019. The cubic root of 1642656121 is about 1179.9100096555.

The spelling of 1642656121 in words is "one billion, six hundred forty-two million, six hundred fifty-six thousand, one hundred twenty-one".