621666 has 12 divisors (see below), whose sum is σ = 1346982. Its totient is φ = 207216.

The previous prime is 621641. The next prime is 621671. The reversal of 621666 is 666126.

621666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 594441 + 27225 = 771^2 + 165^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a nude number because it is divisible by every one of its digits.

It is a plaindrome in base 14.

It is an unprimeable number.

621666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17251 + ... + 17286.

2⁶²¹⁶⁶⁶ is an apocalyptic number.

621666 is an abundant number, since it is smaller than the sum of its proper divisors (725316).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

621666 is a wasteful number, since it uses less digits than its factorization.

621666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34545 (or 34542 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 621666 is about 788.4579887350. The cubic root of 621666 is about 85.3464979418.

It can be divided in two parts, 62 and 1666, that added together give a cube (1728 = 12³).

The spelling of 621666 in words is "six hundred twenty-one thousand, six hundred sixty-six".