21780488 has 8 divisors (see below), whose sum is σ = 40838430. Its totient is φ = 10890240.

The previous prime is 21780487. The next prime is 21780491. The reversal of 21780488 is 88408712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21548164 + 232324 = 4642^2 + 482^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1361273 + ... + 1361288.

Almost surely, 2^21780488 is an apocalyptic number.

It is an amenable number.

21780488 is a deficient number, since it is larger than the sum of its proper divisors (19057942).

21780488 is a wasteful number, since it uses less digits than its factorization.

21780488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2722567 (or 2722563 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 38.

The square root of 21780488 is about 4666.9570385852. The cubic root of 21780488 is about 279.2688748891.

The spelling of 21780488 in words is "twenty-one million, seven hundred eighty thousand, four hundred eighty-eight".