21575380 has 96 divisors (see below), whose sum is σ = 52254720. Its totient is φ = 7434240.

The previous prime is 21575377. The next prime is 21575387. The reversal of 21575380 is 8357512.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21575387) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 242376 + ... + 242464.

It is an arithmetic number, because the mean of its divisors is an integer number (544320).

Almost surely, 2^21575380 is an apocalyptic number.

21575380 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 21575380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26127360).

21575380 is an abundant number, since it is smaller than the sum of its proper divisors (30679340).

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

21575380 is a wasteful number, since it uses less digits than its factorization.

21575380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 31.

The square root of 21575380 is about 4644.9305699870. The cubic root of 21575380 is about 278.3894787553.

The spelling of 21575380 in words is "twenty-one million, five hundred seventy-five thousand, three hundred eighty".