21623530 has 8 divisors (see below), whose sum is σ = 38922372. Its totient is φ = 8649408.

The previous prime is 21623509. The next prime is 21623533. The reversal of 21623530 is 3532612.

It can be written as a sum of positive squares in 2 ways, for example, as 21335161 + 288369 = 4619^2 + 537^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21623533) 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, 1081167 + ... + 1081186.

Almost surely, 2^21623530 is an apocalyptic number.

21623530 is a deficient number, since it is larger than the sum of its proper divisors (17298842).

21623530 is a wasteful number, since it uses less digits than its factorization.

21623530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2162360.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21623530 is about 4650.1107513693. The cubic root of 21623530 is about 278.5964197860.

The spelling of 21623530 in words is "twenty-one million, six hundred twenty-three thousand, five hundred thirty".