21042534 has 8 divisors (see below), whose sum is σ = 42085080. Its totient is φ = 7014176.

The previous prime is 21042533. The next prime is 21042551. The reversal of 21042534 is 43524012.

It is a sphenic number, since it is the product of 3 distinct primes.

21042534 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 21042534.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042533) 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, 1753539 + ... + 1753550.

It is an arithmetic number, because the mean of its divisors is an integer number (5260635).

Almost surely, 2^21042534 is an apocalyptic number.

21042534 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21042534 is a wasteful number, since it uses less digits than its factorization.

21042534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3507094.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21042534 is about 4587.2141872819. The cubic root of 21042534 is about 276.0785588178.

Adding to 21042534 its reverse (43524012), we get a palindrome (64566546).

The spelling of 21042534 in words is "twenty-one million, forty-two thousand, five hundred thirty-four".