21151644231 has 16 divisors (see below), whose sum is σ = 28739753856. Its totient is φ = 13832416416.

The previous prime is 21151644197. The next prime is 21151644271. The reversal of 21151644231 is 13244615112.

It is not a de Polignac number, because 21151644231 - 2⁶ = 21151644167 is a prime.

It is a super-2 number, since 2×21151644231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151644271) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1187316 + ... + 1204998.

It is an arithmetic number, because the mean of its divisors is an integer number (1796234616).

Almost surely, 2^21151644231 is an apocalyptic number.

21151644231 is a deficient number, since it is larger than the sum of its proper divisors (7588109625).

21151644231 is a wasteful number, since it uses less digits than its factorization.

21151644231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25262.

The product of its digits is 5760, while the sum is 30.

The spelling of 21151644231 in words is "twenty-one billion, one hundred fifty-one million, six hundred forty-four thousand, two hundred thirty-one".