21545464 has 8 divisors (see below), whose sum is σ = 40397760. Its totient is φ = 10772728.

The previous prime is 21545441. The next prime is 21545471. The reversal of 21545464 is 46454512.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 1346584 + ... + 1346599.

It is an arithmetic number, because the mean of its divisors is an integer number (5049720).

Almost surely, 2^21545464 is an apocalyptic number.

It is an amenable number.

21545464 is a deficient number, since it is larger than the sum of its proper divisors (18852296).

21545464 is a wasteful number, since it uses less digits than its factorization.

21545464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2693189 (or 2693185 counting only the distinct ones).

The product of its digits is 19200, while the sum is 31.

The square root of 21545464 is about 4641.7091679682. The cubic root of 21545464 is about 278.2607494367.

Adding to 21545464 its reverse (46454512), we get a palindrome (67999976).

The spelling of 21545464 in words is "twenty-one million, five hundred forty-five thousand, four hundred sixty-four".