21643542 has 24 divisors (see below), whose sum is σ = 47109816. Its totient is φ = 7181376.

The previous prime is 21643519. The next prime is 21643607. The reversal of 21643542 is 24534612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1438 + ... + 6734.

It is an arithmetic number, because the mean of its divisors is an integer number (1962909).

Almost surely, 2^21643542 is an apocalyptic number.

21643542 is an abundant number, since it is smaller than the sum of its proper divisors (25466274).

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

21643542 is a wasteful number, since it uses less digits than its factorization.

21643542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5532 (or 5529 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21643542 is about 4652.2620304536. The cubic root of 21643542 is about 278.6823378040.

The spelling of 21643542 in words is "twenty-one million, six hundred forty-three thousand, five hundred forty-two".