1662786661 has 2 divisors, whose sum is σ = 1662786662. Its totient is φ = 1662786660.

The previous prime is 1662786641. The next prime is 1662786667. The reversal of 1662786661 is 1666872661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1259540100 + 403246561 = 35490^2 + 20081^2 .

It is a cyclic number.

It is not a de Polignac number, because 1662786661 - 2²⁷ = 1528568933 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1662786667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 831393330 + 831393331.

It is an arithmetic number, because the mean of its divisors is an integer number (831393331).

Almost surely, 2^1662786661 is an apocalyptic number.

It is an amenable number.

1662786661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1662786661 is an equidigital number, since it uses as much as digits as its factorization.

1662786661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 49.

The square root of 1662786661 is about 40777.2811869551. The cubic root of 1662786661 is about 1184.7103355327.

The spelling of 1662786661 in words is "one billion, six hundred sixty-two million, seven hundred eighty-six thousand, six hundred sixty-one".