21257064 has 24 divisors (see below), whose sum is σ = 57571410. Its totient is φ = 7085664.

The previous prime is 21257059. The next prime is 21257077. The reversal of 21257064 is 46075212.

It can be written as a sum of positive squares in only one way, i.e., 20520900 + 736164 = 4530^2 + 858^2 .

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

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 5 ways as a sum of consecutive naturals, for example, 147547 + ... + 147690.

Almost surely, 2^21257064 is an apocalyptic number.

21257064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21257064 is an abundant number, since it is smaller than the sum of its proper divisors (36314346).

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

21257064 is a wasteful number, since it uses less digits than its factorization.

21257064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295249 (or 295242 counting only the distinct ones).

The product of its (nonzero) digits is 3360, while the sum is 27.

The square root of 21257064 is about 4610.5383633584. The cubic root of 21257064 is about 277.0136013166.

The spelling of 21257064 in words is "twenty-one million, two hundred fifty-seven thousand, sixty-four".