21421380 has 48 divisors (see below), whose sum is σ = 60286464. Its totient is φ = 5683200.

The previous prime is 21421373. The next prime is 21421397. The reversal of 21421380 is 8312412.

It is a super-2 number, since 2×21421380² = 917751042208800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12580 + ... + 14180.

It is an arithmetic number, because the mean of its divisors is an integer number (1255968).

Almost surely, 2^21421380 is an apocalyptic number.

21421380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421380 is an abundant number, since it is smaller than the sum of its proper divisors (38865084).

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

21421380 is a wasteful number, since it uses less digits than its factorization.

21421380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1836 (or 1834 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21421380 is about 4628.3236706177. The cubic root of 21421380 is about 277.7255369610.

Adding to 21421380 its reverse (8312412), we get a palindrome (29733792).

The spelling of 21421380 in words is "twenty-one million, four hundred twenty-one thousand, three hundred eighty".