21506298774 has 16 divisors (see below), whose sum is σ = 43031852208. Its totient is φ = 7165557152.

The previous prime is 21506298719. The next prime is 21506298799. The reversal of 21506298774 is 47789260512.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 787737 + ... + 814580.

It is an arithmetic number, because the mean of its divisors is an integer number (2689490763).

Almost surely, 2^21506298774 is an apocalyptic number.

21506298774 is an abundant number, since it is smaller than the sum of its proper divisors (21525553434).

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

21506298774 is a wasteful number, since it uses less digits than its factorization.

21506298774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1604559.

The product of its (nonzero) digits is 1693440, while the sum is 51.

The spelling of 21506298774 in words is "twenty-one billion, five hundred six million, two hundred ninety-eight thousand, seven hundred seventy-four".