81630161554 has 4 divisors (see below), whose sum is σ = 122445242334. Its totient is φ = 40815080776.

The previous prime is 81630161549. The next prime is 81630161579. The reversal of 81630161554 is 45516103618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 45516103618 = 2 ⋅22758051809.

It can be written as a sum of positive squares in only one way, i.e., 49166410225 + 32463751329 = 221735^2 + 180177^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20407540387 + ... + 20407540390.

Almost surely, 2^81630161554 is an apocalyptic number.

81630161554 is a deficient number, since it is larger than the sum of its proper divisors (40815080780).

81630161554 is a wasteful number, since it uses less digits than its factorization.

81630161554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40815080779.

The product of its (nonzero) digits is 86400, while the sum is 40.

The spelling of 81630161554 in words is "eighty-one billion, six hundred thirty million, one hundred sixty-one thousand, five hundred fifty-four".