21461660 has 24 divisors (see below), whose sum is σ = 49167216. Its totient is φ = 7804160.

The previous prime is 21461647. The next prime is 21461669. The reversal of 21461660 is 6616412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21461669) 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, 48557 + ... + 48996.

It is an arithmetic number, because the mean of its divisors is an integer number (2048634).

Almost surely, 2^21461660 is an apocalyptic number.

21461660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21461660 is an abundant number, since it is smaller than the sum of its proper divisors (27705556).

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

21461660 is a wasteful number, since it uses less digits than its factorization.

21461660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97573 (or 97571 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 21461660 is about 4632.6730944456. The cubic root of 21461660 is about 277.8995030361.

The spelling of 21461660 in words is "twenty-one million, four hundred sixty-one thousand, six hundred sixty".