21061555876 has 27 divisors (see below), whose sum is σ = 37183101249. Its totient is φ = 10438622928.

The previous prime is 21061555811. The next prime is 21061555877. The reversal of 21061555876 is 67855516012.

The square root of 21061555876 is 145126.

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

It can be written as a sum of positive squares in only one way, i.e., 2467506276 + 18594049600 = 49674^2 + 136360^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21061555877) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 43247305 + ... + 43247791.

Almost surely, 2^21061555876 is an apocalyptic number.

21061555876 is the 145126-th square number.

It is an amenable number.

21061555876 is a deficient number, since it is larger than the sum of its proper divisors (16121545373).

21061555876 is an frugal number, since it uses more digits than its factorization.

21061555876 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1276 (or 638 counting only the distinct ones).

The product of its (nonzero) digits is 504000, while the sum is 46.

The spelling of 21061555876 in words is "twenty-one billion, sixty-one million, five hundred fifty-five thousand, eight hundred seventy-six".