21457530 has 24 divisors (see below), whose sum is σ = 55789812. Its totient is φ = 5721984.

The previous prime is 21457523. The next prime is 21457603. The reversal of 21457530 is 3575412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20985561 + 471969 = 4581^2 + 687^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21457494 and 21457503.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 119119 + ... + 119298.

Almost surely, 2^21457530 is an apocalyptic number.

21457530 is an abundant number, since it is smaller than the sum of its proper divisors (34332282).

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

21457530 is a wasteful number, since it uses less digits than its factorization.

21457530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238430 (or 238427 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21457530 is about 4632.2273260279. The cubic root of 21457530 is about 277.8816759190.

The spelling of 21457530 in words is "twenty-one million, four hundred fifty-seven thousand, five hundred thirty".