621649 has 4 divisors (see below), whose sum is σ = 710464. Its totient is φ = 532836.

The previous prime is 621641. The next prime is 621671. The reversal of 621649 is 946126.

621649 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 621649 - 2³ = 621641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (621641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44397 + ... + 44410.

It is an arithmetic number, because the mean of its divisors is an integer number (177616).

2⁶²¹⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

621649 is a deficient number, since it is larger than the sum of its proper divisors (88815).

621649 is an equidigital number, since it uses as much as digits as its factorization.

621649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88814.

The product of its digits is 2592, while the sum is 28.

The square root of 621649 is about 788.4472081249. The cubic root of 621649 is about 85.3457199765.

It can be divided in two parts, 62 and 1649, that added together give a triangular number (1711 = T₅₈).

The spelling of 621649 in words is "six hundred twenty-one thousand, six hundred forty-nine".