21300781 has 8 divisors (see below), whose sum is σ = 22106304. Its totient is φ = 20509440.

The previous prime is 21300757. The next prime is 21300791. The reversal of 21300781 is 18700312.

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 21300781 - 2⁵ = 21300749 is a prime.

It is a super-2 number, since 2×21300781² = 907446542419922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21300791) 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, 436 + ... + 6541.

It is an arithmetic number, because the mean of its divisors is an integer number (2763288).

Almost surely, 2^21300781 is an apocalyptic number.

It is an amenable number.

21300781 is a deficient number, since it is larger than the sum of its proper divisors (805523).

21300781 is an equidigital number, since it uses as much as digits as its factorization.

21300781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7091.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21300781 is about 4615.2769147690. The cubic root of 21300781 is about 277.2033721333.

The spelling of 21300781 in words is "twenty-one million, three hundred thousand, seven hundred eighty-one".