42015521 has 4 divisors (see below), whose sum is σ = 42233412. Its totient is φ = 41797632.

The previous prime is 42015487. The next prime is 42015527. The reversal of 42015521 is 12551024.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27300625 + 14714896 = 5225^2 + 3836^2 .

It is a cyclic number.

It is not a de Polignac number, because 42015521 - 2¹⁴ = 41999137 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 42015493 and 42015502.

It is not an unprimeable number, because it can be changed into a prime (42015527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 108656 + ... + 109041.

It is an arithmetic number, because the mean of its divisors is an integer number (10558353).

Almost surely, 2^42015521 is an apocalyptic number.

It is an amenable number.

42015521 is a deficient number, since it is larger than the sum of its proper divisors (217891).

42015521 is a wasteful number, since it uses less digits than its factorization.

42015521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217890.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 42015521 is about 6481.9380589450. The cubic root of 42015521 is about 347.6454777942.

Adding to 42015521 its reverse (12551024), we get a palindrome (54566545).

The spelling of 42015521 in words is "forty-two million, fifteen thousand, five hundred twenty-one".