21631363 has 4 divisors (see below), whose sum is σ = 23295328. Its totient is φ = 19967400.

The previous prime is 21631349. The next prime is 21631387. The reversal of 21631363 is 36313612.

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

It is a cyclic number.

It is not a de Polignac number, because 21631363 - 2¹³ = 21623171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21631663) 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, 831963 + ... + 831988.

It is an arithmetic number, because the mean of its divisors is an integer number (5823832).

Almost surely, 2^21631363 is an apocalyptic number.

21631363 is a deficient number, since it is larger than the sum of its proper divisors (1663965).

21631363 is a wasteful number, since it uses less digits than its factorization.

21631363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663964.

The product of its digits is 1944, while the sum is 25.

The square root of 21631363 is about 4650.9529131136. The cubic root of 21631363 is about 278.6300557111.

Adding to 21631363 its reverse (36313612), we get a palindrome (57944975).

The spelling of 21631363 in words is "twenty-one million, six hundred thirty-one thousand, three hundred sixty-three".