21290564 has 12 divisors (see below), whose sum is σ = 39219600. Its totient is φ = 10084968.

The previous prime is 21290551. The next prime is 21290567. The reversal of 21290564 is 46509212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21290567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139994 + ... + 140145.

It is an arithmetic number, because the mean of its divisors is an integer number (3268300).

Almost surely, 2^21290564 is an apocalyptic number.

It is an amenable number.

21290564 is a deficient number, since it is larger than the sum of its proper divisors (17929036).

21290564 is a wasteful number, since it uses less digits than its factorization.

21290564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280162 (or 280160 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21290564 is about 4614.1699145133. The cubic root of 21290564 is about 277.1590444973.

Adding to 21290564 its reverse (46509212), we get a palindrome (67799776).

The spelling of 21290564 in words is "twenty-one million, two hundred ninety thousand, five hundred sixty-four".