21307464 has 24 divisors (see below), whose sum is σ = 57707910. Its totient is φ = 7102464.

The previous prime is 21307457. The next prime is 21307469. The reversal of 21307464 is 46470312.

It can be written as a sum of positive squares in only one way, i.e., 10692900 + 10614564 = 3270^2 + 3258^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21307464² = 908016044222592, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307469) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 147897 + ... + 148040.

Almost surely, 2^21307464 is an apocalyptic number.

21307464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21307464 is an abundant number, since it is smaller than the sum of its proper divisors (36400446).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21307464 is a wasteful number, since it uses less digits than its factorization.

21307464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295949 (or 295942 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 21307464 is about 4616.0008665510. Note that the first 3 decimals coincide. The cubic root of 21307464 is about 277.2323594339.

Adding to 21307464 its reverse (46470312), we get a palindrome (67777776).

The spelling of 21307464 in words is "twenty-one million, three hundred seven thousand, four hundred sixty-four".