21678741 has 24 divisors (see below), whose sum is σ = 36152064. Its totient is φ = 12261600.

The previous prime is 21678733. The next prime is 21678763. The reversal of 21678741 is 14787612.

It is not a de Polignac number, because 21678741 - 2³ = 21678733 is a prime.

It is a super-2 number, since 2×21678741² = 939935622690162, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21678696 and 21678705.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4660 + ... + 8066.

It is an arithmetic number, because the mean of its divisors is an integer number (1506336).

Almost surely, 2^21678741 is an apocalyptic number.

21678741 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21678741 is a deficient number, since it is larger than the sum of its proper divisors (14473323).

21678741 is a wasteful number, since it uses less digits than its factorization.

21678741 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3521 (or 3518 counting only the distinct ones).

The product of its digits is 18816, while the sum is 36.

The square root of 21678741 is about 4656.0434920649. The cubic root of 21678741 is about 278.8333301377.

The spelling of 21678741 in words is "twenty-one million, six hundred seventy-eight thousand, seven hundred forty-one".