21010464 has 36 divisors (see below), whose sum is σ = 59749326. Its totient is φ = 7003392.

The previous prime is 21010441. The next prime is 21010469. The reversal of 21010464 is 46401012.

It can be written as a sum of positive squares in only one way, i.e., 18147600 + 2862864 = 4260^2 + 1692^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21010469) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36189 + ... + 36764.

Almost surely, 2^21010464 is an apocalyptic number.

21010464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21010464 is an abundant number, since it is smaller than the sum of its proper divisors (38738862).

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

21010464 is a wasteful number, since it uses less digits than its factorization.

21010464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72969 (or 72958 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21010464 is about 4583.7172687678. The cubic root of 21010464 is about 275.9382344458.

Adding to 21010464 its reverse (46401012), we get a palindrome (67411476).

The spelling of 21010464 in words is "twenty-one million, ten thousand, four hundred sixty-four".