1664867639 has 2 divisors, whose sum is σ = 1664867640. Its totient is φ = 1664867638.

The previous prime is 1664867623. The next prime is 1664867653. The reversal of 1664867639 is 9367684661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1664867639 - 2⁴ = 1664867623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664867339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832433819 + 832433820.

It is an arithmetic number, because the mean of its divisors is an integer number (832433820).

Almost surely, 2^1664867639 is an apocalyptic number.

1664867639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664867639 is an equidigital number, since it uses as much as digits as its factorization.

1664867639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7838208, while the sum is 56.

The square root of 1664867639 is about 40802.7895982615. The cubic root of 1664867639 is about 1185.2043512819.

The spelling of 1664867639 in words is "one billion, six hundred sixty-four million, eight hundred sixty-seven thousand, six hundred thirty-nine".