21462561 has 6 divisors (see below), whose sum is σ = 31001490. Its totient is φ = 14308368.

The previous prime is 21462541. The next prime is 21462563. The reversal of 21462561 is 16526412.

It can be written as a sum of positive squares in only one way, i.e., 11350161 + 10112400 = 3369^2 + 3180^2 .

It is not a de Polignac number, because 21462561 - 2⁷ = 21462433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21462563) 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 5 ways as a sum of consecutive naturals, for example, 1192356 + ... + 1192373.

It is an arithmetic number, because the mean of its divisors is an integer number (5166915).

Almost surely, 2^21462561 is an apocalyptic number.

It is an amenable number.

21462561 is a deficient number, since it is larger than the sum of its proper divisors (9538929).

21462561 is a wasteful number, since it uses less digits than its factorization.

21462561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2384735 (or 2384732 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21462561 is about 4632.7703374979. The cubic root of 21462561 is about 277.9033918926.

Adding to 21462561 its reverse (16526412), we get a palindrome (37988973).

The spelling of 21462561 in words is "twenty-one million, four hundred sixty-two thousand, five hundred sixty-one".