21254740 has 24 divisors (see below), whose sum is σ = 48069000. Its totient is φ = 7847808.

The previous prime is 21254729. The next prime is 21254789. The reversal of 21254740 is 4745212.

It can be written as a sum of positive squares in 4 ways, for example, as 715716 + 20539024 = 846^2 + 4532^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40615 + ... + 41134.

It is an arithmetic number, because the mean of its divisors is an integer number (2002875).

Almost surely, 2^21254740 is an apocalyptic number.

21254740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21254740 is an abundant number, since it is smaller than the sum of its proper divisors (26814260).

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

21254740 is a wasteful number, since it uses less digits than its factorization.

21254740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81771 (or 81769 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21254740 is about 4610.2863251646. The cubic root of 21254740 is about 277.0035058009.

Adding to 21254740 its reverse (4745212), we get a palindrome (25999952).

The spelling of 21254740 in words is "twenty-one million, two hundred fifty-four thousand, seven hundred forty".