21542757 has 8 divisors (see below), whose sum is σ = 30413376. Its totient is φ = 13516992.

The previous prime is 21542687. The next prime is 21542761. The reversal of 21542757 is 75724512.

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

It is not a de Polignac number, because 21542757 - 2¹¹ = 21540709 is a prime.

It is a super-2 number, since 2×21542757² = 928180758322098, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542767) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 211153 + ... + 211254.

It is an arithmetic number, because the mean of its divisors is an integer number (3801672).

Almost surely, 2^21542757 is an apocalyptic number.

It is an amenable number.

21542757 is a deficient number, since it is larger than the sum of its proper divisors (8870619).

21542757 is a wasteful number, since it uses less digits than its factorization.

21542757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422427.

The product of its digits is 19600, while the sum is 33.

The square root of 21542757 is about 4641.4175636329. The cubic root of 21542757 is about 278.2490952683.

The spelling of 21542757 in words is "twenty-one million, five hundred forty-two thousand, seven hundred fifty-seven".