21017542 has 32 divisors (see below), whose sum is σ = 41090112. Its totient is φ = 7824384.

The previous prime is 21017537. The next prime is 21017567. The reversal of 21017542 is 24571012.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 303 + ... + 6490.

It is an arithmetic number, because the mean of its divisors is an integer number (1284066).

Almost surely, 2^21017542 is an apocalyptic number.

21017542 is a deficient number, since it is larger than the sum of its proper divisors (20072570).

21017542 is a wasteful number, since it uses less digits than its factorization.

21017542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6832.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21017542 is about 4584.4892845332. The cubic root of 21017542 is about 275.9692169687.

Adding to 21017542 its reverse (24571012), we get a palindrome (45588554).

The spelling of 21017542 in words is "twenty-one million, seventeen thousand, five hundred forty-two".