21542810 has 8 divisors (see below), whose sum is σ = 38777076. Its totient is φ = 8617120.

The previous prime is 21542803. The next prime is 21542813. The reversal of 21542810 is 1824512.

It can be written as a sum of positive squares in 2 ways, for example, as 20584369 + 958441 = 4537^2 + 979^2 .

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

It is a super-2 number, since 2×21542810² = 928185325392200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21542813) 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 3 ways as a sum of consecutive naturals, for example, 1077131 + ... + 1077150.

Almost surely, 2^21542810 is an apocalyptic number.

21542810 is a deficient number, since it is larger than the sum of its proper divisors (17234266).

21542810 is a wasteful number, since it uses less digits than its factorization.

21542810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2154288.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21542810 is about 4641.4232730920. The cubic root of 21542810 is about 278.2493234531.

The spelling of 21542810 in words is "twenty-one million, five hundred forty-two thousand, eight hundred ten".