21678461 has 8 divisors (see below), whose sum is σ = 24840384. Its totient is φ = 18532800.

The previous prime is 21678439. The next prime is 21678479. The reversal of 21678461 is 16487612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21678461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678401) 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, 1055 + ... + 6668.

It is an arithmetic number, because the mean of its divisors is an integer number (3105048).

Almost surely, 2^21678461 is an apocalyptic number.

It is an amenable number.

21678461 is a deficient number, since it is larger than the sum of its proper divisors (3161923).

21678461 is an equidigital number, since it uses as much as digits as its factorization.

21678461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8131.

The product of its digits is 16128, while the sum is 35.

The square root of 21678461 is about 4656.0134235202. The cubic root of 21678461 is about 278.8321296733.

The spelling of 21678461 in words is "twenty-one million, six hundred seventy-eight thousand, four hundred sixty-one".