21655460 has 24 divisors (see below), whose sum is σ = 47045880. Its totient is φ = 8363264.

The previous prime is 21655457. The next prime is 21655463. The reversal of 21655460 is 6455612.

It is an interprime number because it is at equal distance from previous prime (21655457) and next prime (21655463).

It can be written as a sum of positive squares in 4 ways, for example, as 3541924 + 18113536 = 1882^2 + 4256^2 .

It is a Harshad number since it is a multiple of its sum of digits (29).

It is not an unprimeable number, because it can be changed into a prime (21655463) 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 7 ways as a sum of consecutive naturals, for example, 18089 + ... + 19248.

It is an arithmetic number, because the mean of its divisors is an integer number (1960245).

Almost surely, 2^21655460 is an apocalyptic number.

21655460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21655460 is an abundant number, since it is smaller than the sum of its proper divisors (25390420).

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

21655460 is a wasteful number, since it uses less digits than its factorization.

21655460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37375 (or 37373 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 21655460 is about 4653.5427364536. The cubic root of 21655460 is about 278.7334804906.

The spelling of 21655460 in words is "twenty-one million, six hundred fifty-five thousand, four hundred sixty".