21457312155 has 64 divisors (see below), whose sum is σ = 38833689600. Its totient is φ = 11239430400.

The previous prime is 21457312141. The next prime is 21457312171. The reversal of 21457312155 is 55121375412.

21457312155 is a `hidden beast` number, since 2 + 14 + 573 + 1 + 21 + 55 = 666.

It is not a de Polignac number, because 21457312155 - 2⁸ = 21457311899 is a prime.

It is a super-2 number, since 2×21457312155² (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 63 ways as a sum of consecutive naturals, for example, 1808352 + ... + 1820178.

It is an arithmetic number, because the mean of its divisors is an integer number (606776400).

Almost surely, 2^21457312155 is an apocalyptic number.

21457312155 is a deficient number, since it is larger than the sum of its proper divisors (17376377445).

21457312155 is a wasteful number, since it uses less digits than its factorization.

21457312155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12081 (or 12075 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

Adding to 21457312155 its reverse (55121375412), we get a palindrome (76578687567).

The spelling of 21457312155 in words is "twenty-one billion, four hundred fifty-seven million, three hundred twelve thousand, one hundred fifty-five".