621066665 has 4 divisors (see below), whose sum is σ = 745280004. Its totient is φ = 496853328.

The previous prime is 621066659. The next prime is 621066671. The reversal of 621066665 is 566660126.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (621066659) and next prime (621066671).

It can be written as a sum of positive squares in 2 ways, for example, as 484924441 + 136142224 = 22021^2 + 11668^2 .

It is a cyclic number.

It is not a de Polignac number, because 621066665 - 2¹² = 621062569 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62106662 + ... + 62106671.

It is an arithmetic number, because the mean of its divisors is an integer number (186320001).

Almost surely, 2^621066665 is an apocalyptic number.

It is an amenable number.

621066665 is a deficient number, since it is larger than the sum of its proper divisors (124213339).

621066665 is a wasteful number, since it uses less digits than its factorization.

621066665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124213338.

The product of its (nonzero) digits is 77760, while the sum is 38.

The square root of 621066665 is about 24921.2091400076. The cubic root of 621066665 is about 853.1906220728.

The spelling of 621066665 in words is "six hundred twenty-one million, sixty-six thousand, six hundred sixty-five".