21546920 has 32 divisors (see below), whose sum is σ = 48663720. Its totient is φ = 8586240.

The previous prime is 21546919. The next prime is 21546923. The reversal of 21546920 is 2964512.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 12773476 + 8773444 = 3574^2 + 2962^2 .

It is a super-2 number, since 2×21546920² = 928539522972800, which contains 22 as substring.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21546923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11660 + ... + 13380.

Almost surely, 2^21546920 is an apocalyptic number.

21546920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21546920 is an abundant number, since it is smaller than the sum of its proper divisors (27116800).

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

21546920 is a wasteful number, since it uses less digits than its factorization.

21546920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2045 (or 2041 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21546920 is about 4641.8660040979. The cubic root of 21546920 is about 278.2670173998.

The spelling of 21546920 in words is "twenty-one million, five hundred forty-six thousand, nine hundred twenty".