21691534 has 8 divisors (see below), whose sum is σ = 33229728. Its totient is φ = 10614960.

The previous prime is 21691531. The next prime is 21691543. The reversal of 21691534 is 43519612.

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

It is a junction number, because it is equal to n+sod(n) for n = 21691496 and 21691505.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21691531) 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, 115287 + ... + 115474.

It is an arithmetic number, because the mean of its divisors is an integer number (4153716).

Almost surely, 2^21691534 is an apocalyptic number.

21691534 is a deficient number, since it is larger than the sum of its proper divisors (11538194).

21691534 is a wasteful number, since it uses less digits than its factorization.

21691534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230810.

The product of its digits is 6480, while the sum is 31.

The square root of 21691534 is about 4657.4170953437. The cubic root of 21691534 is about 278.8881674758. Note that the first 3 decimals are identical.

The spelling of 21691534 in words is "twenty-one million, six hundred ninety-one thousand, five hundred thirty-four".