21555034077 has 12 divisors (see below), whose sum is σ = 30530084096. Its totient is φ = 13524726720.

The previous prime is 21555034051. The next prime is 21555034097. The reversal of 21555034077 is 77043055512.

It is a happy number.

It is not a de Polignac number, because 21555034077 - 2⁶ = 21555034013 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 (21555034027) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12429949 + ... + 12431682.

Almost surely, 2^21555034077 is an apocalyptic number.

It is an amenable number.

21555034077 is a deficient number, since it is larger than the sum of its proper divisors (8975050019).

21555034077 is a wasteful number, since it uses less digits than its factorization.

21555034077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24861668 (or 24861651 counting only the distinct ones).

The product of its (nonzero) digits is 147000, while the sum is 39.

Adding to 21555034077 its reverse (77043055512), we get a palindrome (98598089589).

The spelling of 21555034077 in words is "twenty-one billion, five hundred fifty-five million, thirty-four thousand, seventy-seven".