8421660 has 144 divisors (see below), whose sum is σ = 28435680. Its totient is φ = 2004480.

The previous prime is 8421653. The next prime is 8421697. The reversal of 8421660 is 661248.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 138030 + ... + 138090.

It is an arithmetic number, because the mean of its divisors is an integer number (197470).

Almost surely, 2^8421660 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 8421660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14217840).

8421660 is an abundant number, since it is smaller than the sum of its proper divisors (20014020).

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

8421660 is a wasteful number, since it uses less digits than its factorization.

8421660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148 (or 143 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 8421660 is about 2902.0096485022. The cubic root of 8421660 is about 203.4538447726.

Subtracting from 8421660 its product of nonzero digits (2304), we obtain a triangular number (8419356 = T₄₁₀₃).

The spelling of 8421660 in words is "eight million, four hundred twenty-one thousand, six hundred sixty".