21061400849 has 4 divisors (see below), whose sum is σ = 21254624820. Its totient is φ = 20868176880.

The previous prime is 21061400819. The next prime is 21061400917. The reversal of 21061400849 is 94800416012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18951652225 + 2109748624 = 137665^2 + 45932^2 .

It is a cyclic number.

It is not a de Polignac number, because 21061400849 - 2⁸ = 21061400593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21061400809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 96611822 + ... + 96612039.

It is an arithmetic number, because the mean of its divisors is an integer number (5313656205).

Almost surely, 2^21061400849 is an apocalyptic number.

It is an amenable number.

21061400849 is a deficient number, since it is larger than the sum of its proper divisors (193223971).

21061400849 is a wasteful number, since it uses less digits than its factorization.

21061400849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193223970.

The product of its (nonzero) digits is 13824, while the sum is 35.

The spelling of 21061400849 in words is "twenty-one billion, sixty-one million, four hundred thousand, eight hundred forty-nine".