21709363 has 4 divisors (see below), whose sum is σ = 23379328. Its totient is φ = 20039400.

The previous prime is 21709349. The next prime is 21709399. The reversal of 21709363 is 36390712.

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-21709363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21709333) 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 3 ways as a sum of consecutive naturals, for example, 834963 + ... + 834988.

It is an arithmetic number, because the mean of its divisors is an integer number (5844832).

Almost surely, 2^21709363 is an apocalyptic number.

21709363 is a deficient number, since it is larger than the sum of its proper divisors (1669965).

21709363 is a wasteful number, since it uses less digits than its factorization.

21709363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1669964.

The product of its (nonzero) digits is 6804, while the sum is 31.

The square root of 21709363 is about 4659.3307459334. The cubic root of 21709363 is about 278.9645557334.

It can be divided in two parts, 217093 and 63, that added together give a square (217156 = 466²).

The spelling of 21709363 in words is "twenty-one million, seven hundred nine thousand, three hundred sixty-three".