21780541 has 8 divisors (see below), whose sum is σ = 22032000. Its totient is φ = 21530880.

The previous prime is 21780533. The next prime is 21780559. The reversal of 21780541 is 14508712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21780541 - 2³ = 21780533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780511) 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, 48285 + ... + 48733.

It is an arithmetic number, because the mean of its divisors is an integer number (2754000).

Almost surely, 2^21780541 is an apocalyptic number.

It is an amenable number.

21780541 is a deficient number, since it is larger than the sum of its proper divisors (251459).

21780541 is a wasteful number, since it uses less digits than its factorization.

21780541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 899.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21780541 is about 4666.9627167999. The cubic root of 21780541 is about 279.2691014105.

The spelling of 21780541 in words is "twenty-one million, seven hundred eighty thousand, five hundred forty-one".