21779460 has 36 divisors (see below), whose sum is σ = 66064908. Its totient is φ = 5807808.

The previous prime is 21779447. The next prime is 21779473. The reversal of 21779460 is 6497712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21779447) and next prime (21779473).

It can be written as a sum of positive squares in 2 ways, for example, as 9290304 + 12489156 = 3048^2 + 3534^2 .

It is a tau number, because it is divible by the number of its divisors (36).

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 60319 + ... + 60678.

Almost surely, 2^21779460 is an apocalyptic number.

21779460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21779460 is an abundant number, since it is smaller than the sum of its proper divisors (44285448).

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

21779460 is a wasteful number, since it uses less digits than its factorization.

21779460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121012 (or 121007 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 36.

The square root of 21779460 is about 4666.8469012814. The cubic root of 21779460 is about 279.2644811565.

The spelling of 21779460 in words is "twenty-one million, seven hundred seventy-nine thousand, four hundred sixty".