21617493 has 8 divisors (see below), whose sum is σ = 30076608. Its totient is φ = 13785024.

The previous prime is 21617461. The next prime is 21617501. The reversal of 21617493 is 39471612.

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

It is not a de Polignac number, because 21617493 - 2⁵ = 21617461 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21617413) 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, 156580 + ... + 156717.

It is an arithmetic number, because the mean of its divisors is an integer number (3759576).

Almost surely, 2^21617493 is an apocalyptic number.

21617493 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21617493 is a deficient number, since it is larger than the sum of its proper divisors (8459115).

21617493 is a wasteful number, since it uses less digits than its factorization.

21617493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 313323.

The product of its digits is 9072, while the sum is 33.

The square root of 21617493 is about 4649.4615817318. The cubic root of 21617493 is about 278.5704905763.

The spelling of 21617493 in words is "twenty-one million, six hundred seventeen thousand, four hundred ninety-three".