21660410 has 8 divisors (see below), whose sum is σ = 38988756. Its totient is φ = 8664160.

The previous prime is 21660409. The next prime is 21660421. The reversal of 21660410 is 1406612.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17648401 + 4012009 = 4201^2 + 2003^2 .

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

It is a super-2 number, since 2×21660410² = 938346722736200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1083011 + ... + 1083030.

Almost surely, 2^21660410 is an apocalyptic number.

21660410 is a deficient number, since it is larger than the sum of its proper divisors (17328346).

21660410 is a wasteful number, since it uses less digits than its factorization.

21660410 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2166048.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21660410 is about 4654.0745589215. The cubic root of 21660410 is about 278.7547164840.

The spelling of 21660410 in words is "twenty-one million, six hundred sixty thousand, four hundred ten".