621638 has 4 divisors (see below), whose sum is σ = 932460. Its totient is φ = 310818.

The previous prime is 621631. The next prime is 621641. The reversal of 621638 is 836126.

621638 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a plaindrome in base 14.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 621638.

It is not an unprimeable number, because it can be changed into a prime (621631) by changing a digit.

621638 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 as a sum of consecutive naturals, namely, 155408 + ... + 155411.

It is an arithmetic number, because the mean of its divisors is an integer number (233115).

2⁶²¹⁶³⁸ is an apocalyptic number.

621638 is a deficient number, since it is larger than the sum of its proper divisors (310822).

621638 is a wasteful number, since it uses less digits than its factorization.

621638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310821.

The product of its digits is 1728, while the sum is 26.

The square root of 621638 is about 788.4402323575. The cubic root of 621638 is about 85.3452165797.

The spelling of 621638 in words is "six hundred twenty-one thousand, six hundred thirty-eight".