21781758074 has 16 divisors (see below), whose sum is σ = 33803416800. Its totient is φ = 10514044464.

The previous prime is 21781758029. The next prime is 21781758077. The reversal of 21781758074 is 47085718712.

It is not an unprimeable number, because it can be changed into a prime (21781758077) 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, 598697 + ... + 634035.

It is an arithmetic number, because the mean of its divisors is an integer number (2112713550).

Almost surely, 2^21781758074 is an apocalyptic number.

21781758074 is a deficient number, since it is larger than the sum of its proper divisors (12021658726).

21781758074 is a wasteful number, since it uses less digits than its factorization.

21781758074 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45997.

The product of its (nonzero) digits is 878080, while the sum is 50.

The spelling of 21781758074 in words is "twenty-one billion, seven hundred eighty-one million, seven hundred fifty-eight thousand, seventy-four".