21054545 has 16 divisors (see below), whose sum is σ = 26514432. Its totient is φ = 16019520.

The previous prime is 21054541. The next prime is 21054559. The reversal of 21054545 is 54545012.

It is not a de Polignac number, because 21054545 - 2² = 21054541 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

21054545 is a modest number, since divided by 4545 gives 2105 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21054541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25235 + ... + 26055.

It is an arithmetic number, because the mean of its divisors is an integer number (1657152).

Almost surely, 2^21054545 is an apocalyptic number.

It is an amenable number.

21054545 is a deficient number, since it is larger than the sum of its proper divisors (5459887).

21054545 is a wasteful number, since it uses less digits than its factorization.

21054545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072.

The product of its (nonzero) digits is 4000, while the sum is 26.

The square root of 21054545 is about 4588.5231828988. The cubic root of 21054545 is about 276.1310770309.

Adding to 21054545 its reverse (54545012), we get a palindrome (75599557).

The spelling of 21054545 in words is "twenty-one million, fifty-four thousand, five hundred forty-five".