21006546 has 16 divisors (see below), whose sum is σ = 45832608. Its totient is φ = 6365600.

The previous prime is 21006523. The next prime is 21006547. The reversal of 21006546 is 64560012.

It is not an unprimeable number, because it can be changed into a prime (21006547) 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, 159075 + ... + 159206.

It is an arithmetic number, because the mean of its divisors is an integer number (2864538).

Almost surely, 2^21006546 is an apocalyptic number.

21006546 is an abundant number, since it is smaller than the sum of its proper divisors (24826062).

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

21006546 is a wasteful number, since it uses less digits than its factorization.

21006546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318297.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21006546 is about 4583.2898664606. The cubic root of 21006546 is about 275.9210811960.

Adding to 21006546 its reverse (64560012), we get a palindrome (85566558).

It can be divided in two parts, 2100 and 6546, that added together give a triangular number (8646 = T₁₃₁).

The spelling of 21006546 in words is "twenty-one million, six thousand, five hundred forty-six".