21487620 has 96 divisors (see below), whose sum is σ = 75027456. Its totient is φ = 4464000.

The previous prime is 21487597. The next prime is 21487667. The reversal of 21487620 is 2678412.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2295 + ... + 6945.

It is an arithmetic number, because the mean of its divisors is an integer number (781536).

Almost surely, 2^21487620 is an apocalyptic number.

21487620 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 21487620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37513728).

21487620 is an abundant number, since it is smaller than the sum of its proper divisors (53539836).

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

21487620 is a wasteful number, since it uses less digits than its factorization.

21487620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4681 (or 4679 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21487620 is about 4635.4740857867. The cubic root of 21487620 is about 278.0115068646.

The spelling of 21487620 in words is "twenty-one million, four hundred eighty-seven thousand, six hundred twenty".