21542507 has 12 divisors (see below), whose sum is σ = 25673256. Its totient is φ = 18012960.

The previous prime is 21542483. The next prime is 21542537. The reversal of 21542507 is 70524512.

21542507 is nontrivially palindromic in base 5.

It is not a de Polignac number, because 21542507 - 2¹⁴ = 21526123 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21542537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3353 + ... + 7370.

It is an arithmetic number, because the mean of its divisors is an integer number (2139438).

Almost surely, 2^21542507 is an apocalyptic number.

21542507 is a deficient number, since it is larger than the sum of its proper divisors (4130749).

21542507 is a wasteful number, since it uses less digits than its factorization.

21542507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10778 (or 10771 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21542507 is about 4641.3906321274. The cubic root of 21542507 is about 278.2480189197.

The spelling of 21542507 in words is "twenty-one million, five hundred forty-two thousand, five hundred seven".