21351264 has 48 divisors (see below), whose sum is σ = 61145280. Its totient is φ = 6469760.

The previous prime is 21351241. The next prime is 21351287. The reversal of 21351264 is 46215312.

It is an interprime number because it is at equal distance from previous prime (21351241) and next prime (21351287).

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

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 in 7 ways as a sum of consecutive naturals, for example, 9054 + ... + 11165.

It is an arithmetic number, because the mean of its divisors is an integer number (1273860).

Almost surely, 2^21351264 is an apocalyptic number.

21351264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21351264 is an abundant number, since it is smaller than the sum of its proper divisors (39794016).

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

21351264 is a wasteful number, since it uses less digits than its factorization.

21351264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20243 (or 20235 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21351264 is about 4620.7427974299. The cubic root of 21351264 is about 277.4221906675.

Adding to 21351264 its reverse (46215312), we get a palindrome (67566576).

The spelling of 21351264 in words is "twenty-one million, three hundred fifty-one thousand, two hundred sixty-four".