21387476 has 18 divisors (see below), whose sum is σ = 41140890. Its totient is φ = 9721360.

The previous prime is 21387473. The next prime is 21387497. The reversal of 21387476 is 67478312.

It can be written as a sum of positive squares in only one way, i.e., 11628100 + 9759376 = 3410^2 + 3124^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387473) 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 5 ways as a sum of consecutive naturals, for example, 21611 + ... + 22578.

It is an arithmetic number, because the mean of its divisors is an integer number (2285605).

Almost surely, 2^21387476 is an apocalyptic number.

It is an amenable number.

21387476 is a deficient number, since it is larger than the sum of its proper divisors (19753414).

21387476 is a wasteful number, since it uses less digits than its factorization.

21387476 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44215 (or 44202 counting only the distinct ones).

The product of its digits is 56448, while the sum is 38.

The square root of 21387476 is about 4624.6595550375. The cubic root of 21387476 is about 277.5789392067.

The spelling of 21387476 in words is "twenty-one million, three hundred eighty-seven thousand, four hundred seventy-six".