21761206555 has 16 divisors (see below), whose sum is σ = 29406348288. Its totient is φ = 15315804000.

The previous prime is 21761206543. The next prime is 21761206561. The reversal of 21761206555 is 55560216712.

It is not a de Polignac number, because 21761206555 - 2²¹ = 21759109403 is a prime.

It is a super-2 number, since 2×21761206555² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6379881 + ... + 6383290.

It is an arithmetic number, because the mean of its divisors is an integer number (1837896768).

Almost surely, 2^21761206555 is an apocalyptic number.

21761206555 is a deficient number, since it is larger than the sum of its proper divisors (7645141733).

21761206555 is a wasteful number, since it uses less digits than its factorization.

21761206555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12763218.

The product of its (nonzero) digits is 126000, while the sum is 40.

The spelling of 21761206555 in words is "twenty-one billion, seven hundred sixty-one million, two hundred six thousand, five hundred fifty-five".