81564002 has 16 divisors (see below), whose sum is σ = 133119672. Its totient is φ = 37255680.

The previous prime is 81564001. The next prime is 81564023. The reversal of 81564002 is 20046518.

It can be written as a sum of positive squares in 4 ways, for example, as 35988001 + 45576001 = 5999^2 + 6751^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (81564001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13649 + ... + 18692.

Almost surely, 2^81564002 is an apocalyptic number.

81564002 is a deficient number, since it is larger than the sum of its proper divisors (51555670).

81564002 is a wasteful number, since it uses less digits than its factorization.

81564002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32453.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 81564002 is about 9031.2790899185. The cubic root of 81564002 is about 433.6767858332.

The spelling of 81564002 in words is "eighty-one million, five hundred sixty-four thousand, two".