21679164 has 60 divisors (see below), whose sum is σ = 61044984. Its totient is φ = 6669216.

The previous prime is 21679159. The next prime is 21679169. The reversal of 21679164 is 46197612.

It is an interprime number because it is at equal distance from previous prime (21679159) and next prime (21679169).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21679169) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1639 + ... + 6785.

Almost surely, 2^21679164 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 21679164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30522492).

21679164 is an abundant number, since it is smaller than the sum of its proper divisors (39365820).

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

21679164 is a wasteful number, since it uses less digits than its factorization.

21679164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5176 (or 5165 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21679164 is about 4656.0889166767. The cubic root of 21679164 is about 278.8351436767.

The spelling of 21679164 in words is "twenty-one million, six hundred seventy-nine thousand, one hundred sixty-four".