21531693 has 8 divisors (see below), whose sum is σ = 30220000. Its totient is φ = 13598928.

The previous prime is 21531689. The next prime is 21531709. The reversal of 21531693 is 39613512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21531693 - 2² = 21531689 is a prime.

It is a super-2 number, since 2×21531693² = 927227606892498, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21531693.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 188818 + ... + 188931.

It is an arithmetic number, because the mean of its divisors is an integer number (3777500).

Almost surely, 2^21531693 is an apocalyptic number.

It is an amenable number.

21531693 is a deficient number, since it is larger than the sum of its proper divisors (8688307).

21531693 is a wasteful number, since it uses less digits than its factorization.

21531693 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 377771.

The product of its digits is 4860, while the sum is 30.

The square root of 21531693 is about 4640.2255333119. The cubic root of 21531693 is about 278.2014524159.

The spelling of 21531693 in words is "twenty-one million, five hundred thirty-one thousand, six hundred ninety-three".