21542743 has 8 divisors (see below), whose sum is σ = 22579200. Its totient is φ = 20514648.

The previous prime is 21542687. The next prime is 21542761. The reversal of 21542743 is 34724512.

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

It is a cyclic number.

It is not a de Polignac number, because 21542743 - 2⁹ = 21542231 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542783) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3538 + ... + 7456.

It is an arithmetic number, because the mean of its divisors is an integer number (2822400).

Almost surely, 2^21542743 is an apocalyptic number.

21542743 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21542743 is a deficient number, since it is larger than the sum of its proper divisors (1036457).

21542743 is a wasteful number, since it uses less digits than its factorization.

21542743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4181.

The product of its digits is 6720, while the sum is 28.

The square root of 21542743 is about 4641.4160554727. The cubic root of 21542743 is about 278.2490349930.

The spelling of 21542743 in words is "twenty-one million, five hundred forty-two thousand, seven hundred forty-three".