21125231964 has 18 divisors (see below), whose sum is σ = 53399892000. Its totient is φ = 7041743976.

The previous prime is 21125231927. The next prime is 21125231969. The reversal of 21125231964 is 46913252112.

21125231964 is a `hidden beast` number, since 2 + 112 + 523 + 19 + 6 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 586811999 = 21125231964 / (2 + 1 + 1 + 2 + 5 + 2 + 3 + 1 + 9 + 6 + 4).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125231969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 293405964 + ... + 293406035.

Almost surely, 2^21125231964 is an apocalyptic number.

It is an amenable number.

21125231964 is an abundant number, since it is smaller than the sum of its proper divisors (32274660036).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21125231964 is a wasteful number, since it uses less digits than its factorization.

21125231964 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 586812009 (or 586812004 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The spelling of 21125231964 in words is "twenty-one billion, one hundred twenty-five million, two hundred thirty-one thousand, nine hundred sixty-four".