21543490 has 16 divisors (see below), whose sum is σ = 38864448. Its totient is φ = 8598256.

The previous prime is 21543461. The next prime is 21543499. The reversal of 21543490 is 9434512.

It is a super-2 number, since 2×21543490² = 928243922760200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21543499) 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, 2889 + ... + 7171.

It is an arithmetic number, because the mean of its divisors is an integer number (2429028).

Almost surely, 2^21543490 is an apocalyptic number.

21543490 is a deficient number, since it is larger than the sum of its proper divisors (17320958).

21543490 is a wasteful number, since it uses less digits than its factorization.

21543490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4793.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21543490 is about 4641.4965259063. The cubic root of 21543490 is about 278.2522510741.

The spelling of 21543490 in words is "twenty-one million, five hundred forty-three thousand, four hundred ninety".