621666623 has 2 divisors, whose sum is σ = 621666624. Its totient is φ = 621666622.

The previous prime is 621666611. The next prime is 621666629. The reversal of 621666623 is 326666126.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 621666623 - 2⁴ = 621666607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (621666629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310833311 + 310833312.

It is an arithmetic number, because the mean of its divisors is an integer number (310833312).

Almost surely, 2^621666623 is an apocalyptic number.

621666623 is a deficient number, since it is larger than the sum of its proper divisors (1).

621666623 is an equidigital number, since it uses as much as digits as its factorization.

621666623 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 38.

The square root of 621666623 is about 24933.2433309427. The cubic root of 621666623 is about 853.4652645170.

The spelling of 621666623 in words is "six hundred twenty-one million, six hundred sixty-six thousand, six hundred twenty-three".