21531367 has 24 divisors (see below), whose sum is σ = 26922672. Its totient is φ = 16972800.

The previous prime is 21531361. The next prime is 21531379. The reversal of 21531367 is 76313512.

It is a de Polignac number, because none of the positive numbers 2^k-21531367 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531361) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 41067 + ... + 41587.

It is an arithmetic number, because the mean of its divisors is an integer number (1121778).

Almost surely, 2^21531367 is an apocalyptic number.

21531367 is a deficient number, since it is larger than the sum of its proper divisors (5391305).

21531367 is a wasteful number, since it uses less digits than its factorization.

21531367 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 579 (or 562 counting only the distinct ones).

The product of its digits is 3780, while the sum is 28.

The square root of 21531367 is about 4640.1904055760. The cubic root of 21531367 is about 278.2000483751.

Adding to 21531367 its reverse (76313512), we get a palindrome (97844879).

The spelling of 21531367 in words is "twenty-one million, five hundred thirty-one thousand, three hundred sixty-seven".