42001521 has 4 divisors (see below), whose sum is σ = 56002032. Its totient is φ = 28001012.

The previous prime is 42001517. The next prime is 42001529. The reversal of 42001521 is 12510024.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 42001521 - 2² = 42001517 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 42001521.

It is not an unprimeable number, because it can be changed into a prime (42001529) 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, 7000251 + ... + 7000256.

It is an arithmetic number, because the mean of its divisors is an integer number (14000508).

Almost surely, 2^42001521 is an apocalyptic number.

It is an amenable number.

42001521 is a deficient number, since it is larger than the sum of its proper divisors (14000511).

42001521 is a wasteful number, since it uses less digits than its factorization.

42001521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14000510.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 42001521 is about 6480.8580450431. The cubic root of 42001521 is about 347.6068604987.

Adding to 42001521 its reverse (12510024), we get a palindrome (54511545).

The spelling of 42001521 in words is "forty-two million, one thousand, five hundred twenty-one".