21519420 has 96 divisors (see below), whose sum is σ = 66382848. Its totient is φ = 5175552.

The previous prime is 21519413. The next prime is 21519427. The reversal of 21519420 is 2491512.

It is an interprime number because it is at equal distance from previous prime (21519413) and next prime (21519427).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21519427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 36367 + ... + 36953.

It is an arithmetic number, because the mean of its divisors is an integer number (691488).

Almost surely, 2^21519420 is an apocalyptic number.

21519420 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 21519420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33191424).

21519420 is an abundant number, since it is smaller than the sum of its proper divisors (44863428).

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

21519420 is a wasteful number, since it uses less digits than its factorization.

21519420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 659 (or 657 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 21519420 is about 4638.9028875371. The cubic root of 21519420 is about 278.1485843738.

The spelling of 21519420 in words is "twenty-one million, five hundred nineteen thousand, four hundred twenty".