21078709061 has 4 divisors (see below), whose sum is σ = 21079023372. Its totient is φ = 21078394752.

The previous prime is 21078709021. The next prime is 21078709097. The reversal of 21078709061 is 16090787012.

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 8996522500 + 12082186561 = 94850^2 + 109919^2 .

It is a cyclic number.

It is not a de Polignac number, because 21078709061 - 2¹⁰ = 21078708037 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21078709021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11660 + ... + 205653.

It is an arithmetic number, because the mean of its divisors is an integer number (5269755843).

Almost surely, 2^21078709061 is an apocalyptic number.

It is an amenable number.

21078709061 is a deficient number, since it is larger than the sum of its proper divisors (314311).

21078709061 is an equidigital number, since it uses as much as digits as its factorization.

21078709061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314310.

The product of its (nonzero) digits is 42336, while the sum is 41.

The spelling of 21078709061 in words is "twenty-one billion, seventy-eight million, seven hundred nine thousand, sixty-one".