21542145 has 32 divisors (see below), whose sum is σ = 38092032. Its totient is φ = 10340352.

The previous prime is 21542119. The next prime is 21542153. The reversal of 21542145 is 54124512.

It is not a de Polignac number, because 21542145 - 2⁸ = 21541889 is a prime.

It is a super-2 number, since 2×21542145² = 928128022402050, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4029 + ... + 7701.

It is an arithmetic number, because the mean of its divisors is an integer number (1190376).

Almost surely, 2^21542145 is an apocalyptic number.

It is an amenable number.

21542145 is a deficient number, since it is larger than the sum of its proper divisors (16549887).

21542145 is a wasteful number, since it uses less digits than its factorization.

21542145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3721.

The product of its digits is 1600, while the sum is 24.

The square root of 21542145 is about 4641.3516350305. The cubic root of 21542145 is about 278.2464603524.

Adding to 21542145 its reverse (54124512), we get a palindrome (75666657).

The spelling of 21542145 in words is "twenty-one million, five hundred forty-two thousand, one hundred forty-five".