21164624 has 40 divisors (see below), whose sum is σ = 44658600. Its totient is φ = 9658368.

The previous prime is 21164593. The next prime is 21164659. The reversal of 21164624 is 42646112.

It can be written as a sum of positive squares in 4 ways, for example, as 3356224 + 17808400 = 1832^2 + 4220^2 .

It is a super-2 number, since 2×21164624² = 895882618122752, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a junction number, because it is equal to n+sod(n) for n = 21164593 and 21164602.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19652 + ... + 20700.

It is an arithmetic number, because the mean of its divisors is an integer number (1116465).

Almost surely, 2^21164624 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 21164624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22329300).

21164624 is an abundant number, since it is smaller than the sum of its proper divisors (23493976).

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

21164624 is a wasteful number, since it uses less digits than its factorization.

21164624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1167 (or 1161 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

The square root of 21164624 is about 4600.5025812404. The cubic root of 21164624 is about 276.6114707393.

It can be divided in two parts, 2116 and 4624, that multiplied together give a square (9784384 = 3128²).

The spelling of 21164624 in words is "twenty-one million, one hundred sixty-four thousand, six hundred twenty-four".