21542642 has 8 divisors (see below), whose sum is σ = 35251632. Its totient is φ = 9792100.

The previous prime is 21542639. The next prime is 21542663. The reversal of 21542642 is 24624512.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489584 + ... + 489627.

It is an arithmetic number, because the mean of its divisors is an integer number (4406454).

Almost surely, 2^21542642 is an apocalyptic number.

21542642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21542642 is a deficient number, since it is larger than the sum of its proper divisors (13708990).

21542642 is a wasteful number, since it uses less digits than its factorization.

21542642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 979224.

The product of its digits is 3840, while the sum is 26.

The square root of 21542642 is about 4641.4051751598. The cubic root of 21542642 is about 278.2486001490.

The spelling of 21542642 in words is "twenty-one million, five hundred forty-two thousand, six hundred forty-two".