621011665 has 4 divisors (see below), whose sum is σ = 745214004. Its totient is φ = 496809328.

The previous prime is 621011641. The next prime is 621011669. The reversal of 621011665 is 566110126.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566110126 = 2 ⋅283055063.

It can be written as a sum of positive squares in 2 ways, for example, as 119968209 + 501043456 = 10953^2 + 22384^2 .

It is a cyclic number.

It is not a de Polignac number, because 621011665 - 2¹⁷ = 620880593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (621011669) by changing a digit.

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, 62101162 + ... + 62101171.

It is an arithmetic number, because the mean of its divisors is an integer number (186303501).

Almost surely, 2^621011665 is an apocalyptic number.

It is an amenable number.

621011665 is a deficient number, since it is larger than the sum of its proper divisors (124202339).

621011665 is a wasteful number, since it uses less digits than its factorization.

621011665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124202338.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 621011665 is about 24920.1056378178. The cubic root of 621011665 is about 853.1654359040.

The spelling of 621011665 in words is "six hundred twenty-one million, eleven thousand, six hundred sixty-five".