21761856 has 42 divisors (see below), whose sum is σ = 62378082. Its totient is φ = 7253760.

The previous prime is 21761849. The next prime is 21761863. The reversal of 21761856 is 65816712.

It is an interprime number because it is at equal distance from previous prime (21761849) and next prime (21761863).

It can be written as a sum of positive squares in only one way, i.e., 20793600 + 968256 = 4560^2 + 984^2 .

It is a super-3 number, since 3×21761856³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21761856.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18315 + ... + 19466.

Almost surely, 2^21761856 is an apocalyptic number.

It is an amenable number.

21761856 is an abundant number, since it is smaller than the sum of its proper divisors (40616226).

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

21761856 is a wasteful number, since it uses less digits than its factorization.

21761856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37799 (or 37786 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21761856 is about 4664.9604499931. The cubic root of 21761856 is about 279.1892191577.

The spelling of 21761856 in words is "twenty-one million, seven hundred sixty-one thousand, eight hundred fifty-six".