21490380 has 96 divisors (see below), whose sum is σ = 70822080. Its totient is φ = 5391360.

The previous prime is 21490319. The next prime is 21490393. The reversal of 21490380 is 8309412.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 8010 + ... + 10350.

It is an arithmetic number, because the mean of its divisors is an integer number (737730).

Almost surely, 2^21490380 is an apocalyptic number.

21490380 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 21490380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35411040).

21490380 is an abundant number, since it is smaller than the sum of its proper divisors (49331700).

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

21490380 is a wasteful number, since it uses less digits than its factorization.

21490380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2376 (or 2368 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21490380 is about 4635.7717804051. The cubic root of 21490380 is about 278.0234095153.

Adding to 21490380 its reverse (8309412), we get a palindrome (29799792).

The spelling of 21490380 in words is "twenty-one million, four hundred ninety thousand, three hundred eighty".