21542530 has 16 divisors (see below), whose sum is σ = 38868984. Its totient is φ = 8596480.

The previous prime is 21542483. The next prime is 21542537. The reversal of 21542530 is 3524512.

It can be written as a sum of positive squares in 4 ways, for example, as 20061441 + 1481089 = 4479^2 + 1217^2 .

It is not an unprimeable number, because it can be changed into a prime (21542537) 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, 2274 + ... + 6946.

Almost surely, 2^21542530 is an apocalyptic number.

21542530 is a deficient number, since it is larger than the sum of its proper divisors (17326454).

21542530 is a wasteful number, since it uses less digits than its factorization.

21542530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5141.

The product of its (nonzero) digits is 1200, while the sum is 22.

The square root of 21542530 is about 4641.3931098324. The cubic root of 21542530 is about 278.2481179442.

The spelling of 21542530 in words is "twenty-one million, five hundred forty-two thousand, five hundred thirty".