21340578 has 48 divisors (see below), whose sum is σ = 51382080. Its totient is φ = 5884704.

The previous prime is 21340567. The next prime is 21340597. The reversal of 21340578 is 87504312.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7275 + ... + 9777.

It is an arithmetic number, because the mean of its divisors is an integer number (1070460).

Almost surely, 2^21340578 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21340578, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25691040).

21340578 is an abundant number, since it is smaller than the sum of its proper divisors (30041502).

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

21340578 is a wasteful number, since it uses less digits than its factorization.

21340578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2551 (or 2544 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 21340578 is about 4619.5863451179. The cubic root of 21340578 is about 277.3759010078.

The spelling of 21340578 in words is "twenty-one million, three hundred forty thousand, five hundred seventy-eight".