21278964 has 24 divisors (see below), whose sum is σ = 56744128. Its totient is φ = 6079680.

The previous prime is 21278963. The next prime is 21278981. The reversal of 21278964 is 46987212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21278963) 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 7 ways as a sum of consecutive naturals, for example, 126577 + ... + 126744.

Almost surely, 2^21278964 is an apocalyptic number.

It is an amenable number.

21278964 is an abundant number, since it is smaller than the sum of its proper divisors (35465164).

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

21278964 is a wasteful number, since it uses less digits than its factorization.

21278964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253335 (or 253333 counting only the distinct ones).

The product of its digits is 48384, while the sum is 39.

The square root of 21278964 is about 4612.9127457605. The cubic root of 21278964 is about 277.1086993618.

The spelling of 21278964 in words is "twenty-one million, two hundred seventy-eight thousand, nine hundred sixty-four".