21681546 has 32 divisors (see below), whose sum is σ = 46717440. Its totient is φ = 6686064.

The previous prime is 21681533. The next prime is 21681547. The reversal of 21681546 is 64518612.

It is not an unprimeable number, because it can be changed into a prime (21681547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2691 + ... + 7113.

It is an arithmetic number, because the mean of its divisors is an integer number (1459920).

Almost surely, 2^21681546 is an apocalyptic number.

21681546 is an abundant number, since it is smaller than the sum of its proper divisors (25035894).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21681546 is a wasteful number, since it uses less digits than its factorization.

21681546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4490.

The product of its digits is 11520, while the sum is 33.

The square root of 21681546 is about 4656.3447037349. The cubic root of 21681546 is about 278.8453556478.

The spelling of 21681546 in words is "twenty-one million, six hundred eighty-one thousand, five hundred forty-six".