1664351642 has 4 divisors (see below), whose sum is σ = 2496527466. Its totient is φ = 832175820.

The previous prime is 1664351617. The next prime is 1664351657. The reversal of 1664351642 is 2461534661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2461534661 = 251 ⋅9806911.

It can be written as a sum of positive squares in only one way, i.e., 1207632001 + 456719641 = 34751^2 + 21371^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1664351596 and 1664351605.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416087909 + ... + 416087912.

Almost surely, 2^1664351642 is an apocalyptic number.

1664351642 is a deficient number, since it is larger than the sum of its proper divisors (832175824).

1664351642 is an equidigital number, since it uses as much as digits as its factorization.

1664351642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 832175823.

The product of its digits is 103680, while the sum is 38.

The square root of 1664351642 is about 40796.4660479312. The cubic root of 1664351642 is about 1185.0818940833.

The spelling of 1664351642 in words is "one billion, six hundred sixty-four million, three hundred fifty-one thousand, six hundred forty-two".