21461904 has 60 divisors (see below), whose sum is σ = 60688576. Its totient is φ = 7079616.

The previous prime is 21461903. The next prime is 21461917. The reversal of 21461904 is 40916412.

It is a super-2 number, since 2×21461904² = 921226646610432, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21461903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14109 + ... + 15555.

Almost surely, 2^21461904 is an apocalyptic number.

21461904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21461904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30344288).

21461904 is an abundant number, since it is smaller than the sum of its proper divisors (39226672).

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

21461904 is a wasteful number, since it uses less digits than its factorization.

21461904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1564 (or 1555 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21461904 is about 4632.6994290586. The cubic root of 21461904 is about 277.9005561889.

The spelling of 21461904 in words is "twenty-one million, four hundred sixty-one thousand, nine hundred four".