21455380 has 24 divisors (see below), whose sum is σ = 45416448. Its totient is φ = 8513568.

The previous prime is 21455363. The next prime is 21455383. The reversal of 21455380 is 8355412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21455383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1684 + ... + 6763.

It is an arithmetic number, because the mean of its divisors is an integer number (1892352).

Almost surely, 2^21455380 is an apocalyptic number.

21455380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21455380 is an abundant number, since it is smaller than the sum of its proper divisors (23961068).

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

21455380 is a wasteful number, since it uses less digits than its factorization.

21455380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8583 (or 8581 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 21455380 is about 4631.9952504293. The cubic root of 21455380 is about 277.8723945531.

The spelling of 21455380 in words is "twenty-one million, four hundred fifty-five thousand, three hundred eighty".