21381763 has 4 divisors (see below), whose sum is σ = 23026528. Its totient is φ = 19737000.

The previous prime is 21381749. The next prime is 21381769. The reversal of 21381763 is 36718312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21381763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21381769) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 822363 + ... + 822388.

It is an arithmetic number, because the mean of its divisors is an integer number (5756632).

Almost surely, 2^21381763 is an apocalyptic number.

21381763 is a deficient number, since it is larger than the sum of its proper divisors (1644765).

21381763 is a wasteful number, since it uses less digits than its factorization.

21381763 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1644764.

The product of its digits is 6048, while the sum is 31.

The square root of 21381763 is about 4624.0418466965. The cubic root of 21381763 is about 277.5542214747.

The spelling of 21381763 in words is "twenty-one million, three hundred eighty-one thousand, seven hundred sixty-three".