21311325555 has 32 divisors (see below), whose sum is σ = 37987306560. Its totient is φ = 10129943040.

The previous prime is 21311325481. The next prime is 21311325587. The reversal of 21311325555 is 55552311312.

It is a happy number.

It is not a de Polignac number, because 21311325555 - 2³² = 17016358259 is a prime.

It is a super-2 number, since 2×21311325555² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1878636 + ... + 1889945.

It is an arithmetic number, because the mean of its divisors is an integer number (1187103330).

Almost surely, 2^21311325555 is an apocalyptic number.

21311325555 is a deficient number, since it is larger than the sum of its proper divisors (16675981005).

21311325555 is a wasteful number, since it uses less digits than its factorization.

21311325555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3768631.

The product of its digits is 22500, while the sum is 33.

Adding to 21311325555 its reverse (55552311312), we get a palindrome (76863636867).

The spelling of 21311325555 in words is "twenty-one billion, three hundred eleven million, three hundred twenty-five thousand, five hundred fifty-five".