21349620 has 72 divisors (see below), whose sum is σ = 68579784. Its totient is φ = 5357568.

The previous prime is 21349591. The next prime is 21349621. The reversal of 21349620 is 2694312.

21349620 is a `hidden beast` number, since 2 + 1 + 34 + 9 + 620 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1954404 + 19395216 = 1398^2 + 4404^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21349621) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 429 + ... + 6548.

It is an arithmetic number, because the mean of its divisors is an integer number (952497).

Almost surely, 2^21349620 is an apocalyptic number.

21349620 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 21349620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34289892).

21349620 is an abundant number, since it is smaller than the sum of its proper divisors (47230164).

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

21349620 is a wasteful number, since it uses less digits than its factorization.

21349620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7009 (or 7004 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21349620 is about 4620.5649005289. The cubic root of 21349620 is about 277.4150701869.

The spelling of 21349620 in words is "twenty-one million, three hundred forty-nine thousand, six hundred twenty".