21621634 has 8 divisors (see below), whose sum is σ = 32578560. Its totient is φ = 10762116.

The previous prime is 21621631. The next prime is 21621641. The reversal of 21621634 is 43612612.

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 = 21621599 and 21621608.

It is not an unprimeable number, because it can be changed into a prime (21621631) 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, 23794 + ... + 24685.

It is an arithmetic number, because the mean of its divisors is an integer number (4072320).

Almost surely, 2^21621634 is an apocalyptic number.

21621634 is a deficient number, since it is larger than the sum of its proper divisors (10956926).

21621634 is a wasteful number, since it uses less digits than its factorization.

21621634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48704.

The product of its digits is 1728, while the sum is 25.

The square root of 21621634 is about 4649.9068807880. The cubic root of 21621634 is about 278.5882768934.

The spelling of 21621634 in words is "twenty-one million, six hundred twenty-one thousand, six hundred thirty-four".