21670660 has 48 divisors (see below), whose sum is σ = 50077440. Its totient is φ = 7811840.

The previous prime is 21670633. The next prime is 21670679. The reversal of 21670660 is 6607612.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29781 + ... + 30499.

It is an arithmetic number, because the mean of its divisors is an integer number (1043280).

Almost surely, 2^21670660 is an apocalyptic number.

21670660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21670660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25038720).

21670660 is an abundant number, since it is smaller than the sum of its proper divisors (28406780).

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

21670660 is a wasteful number, since it uses less digits than its factorization.

21670660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 876 (or 874 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 21670660 is about 4655.1756143029. The cubic root of 21670660 is about 278.7986797218.

It can be divided in two parts, 216 and 70660, that added together give a triangular number (70876 = T₃₇₆).

The spelling of 21670660 in words is "twenty-one million, six hundred seventy thousand, six hundred sixty".