81372126564 has 27 divisors (see below), whose sum is σ = 205694979763. Its totient is φ = 27123471672.

The previous prime is 81372126559. The next prime is 81372126569. The reversal of 81372126564 is 46562127318.

The square root of 81372126564 is 285258.

It is a perfect power (a square), and thus also a powerful number.

81372126564 is a `hidden beast` number, since 8 + 1 + 3 + 72 + 12 + 6 + 564 = 666.

It is an interprime number because it is at equal distance from previous prime (81372126559) and next prime (81372126569).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81372126569) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1687777 + ... + 1735319.

Almost surely, 2^81372126564 is an apocalyptic number.

81372126564 is the 285258-th square number.

It is an amenable number.

81372126564 is an abundant number, since it is smaller than the sum of its proper divisors (124322853199).

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

81372126564 is an frugal number, since it uses more digits than its factorization.

81372126564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95096 (or 47548 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

It can be divided in two parts, 81372 and 126564, that added together give a square (207936 = 456²).

The spelling of 81372126564 in words is "eighty-one billion, three hundred seventy-two million, one hundred twenty-six thousand, five hundred sixty-four".