20942457621849 has 15 divisors (see below), whose sum is σ = 31284473528847. Its totient is φ = 13961610956808.

The previous prime is 20942457621823. The next prime is 20942457621853. The reversal of 20942457621849 is 94812675424902.

It is a happy number.

The square root of 20942457621849 is 4576293.

It is a perfect power (a square), and thus also a powerful number.

20942457621849 is a `hidden beast` number, since 2 + 0 + 9 + 4 + 2 + 4 + 576 + 2 + 18 + 49 = 666.

It can be written as a sum of positive squares in only one way, i.e., 5385207566025 + 15557250055824 = 2320605^2 + 3944268^2 .

It is not a de Polignac number, because 20942457621849 - 2¹⁷ = 20942457490777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20942457421849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 40932399 + ... + 41440875.

Almost surely, 2^{20942457621849} is an apocalyptic number.

20942457621849 is the 4576293-rd square number.

20942457621849 is the 2288147-th centered octagonal number.

It is an amenable number.

20942457621849 is a deficient number, since it is larger than the sum of its proper divisors (10342015906998).

20942457621849 is an frugal number, since it uses more digits than its factorization.

20942457621849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1016966 (or 508480 counting only the distinct ones).

The product of its (nonzero) digits is 69672960, while the sum is 63.

The spelling of 20942457621849 in words is "twenty trillion, nine hundred forty-two billion, four hundred fifty-seven million, six hundred twenty-one thousand, eight hundred forty-nine".