621690 has 64 divisors (see below), whose sum is σ = 1679616. Its totient is φ = 146432.

The previous prime is 621679. The next prime is 621697. The reversal of 621690 is 96126.

It is a super-2 number, since 2×621690² = 772996912200, which contains 22 as substring.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 621690.

It is not an unprimeable number, because it can be changed into a prime (621697) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11704 + ... + 11756.

It is an arithmetic number, because the mean of its divisors is an integer number (26244).

2⁶²¹⁶⁹⁰ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 621690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (839808).

621690 is an abundant number, since it is smaller than the sum of its proper divisors (1057926).

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

621690 is a wasteful number, since it uses less digits than its factorization.

621690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103.

The product of its (nonzero) digits is 648, while the sum is 24.

The square root of 621690 is about 788.4732081688. The cubic root of 621690 is about 85.3475962216.

The spelling of 621690 in words is "six hundred twenty-one thousand, six hundred ninety".