81220861408 has 12 divisors (see below), whose sum is σ = 159903570960. Its totient is φ = 40610430688.

The previous prime is 81220861387. The next prime is 81220861433. The reversal of 81220861408 is 80416802218.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1269075928 + ... + 1269075991.

It is an arithmetic number, because the mean of its divisors is an integer number (13325297580).

Almost surely, 2^81220861408 is an apocalyptic number.

It is an amenable number.

81220861408 is a deficient number, since it is larger than the sum of its proper divisors (78682709552).

81220861408 is a wasteful number, since it uses less digits than its factorization.

81220861408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2538151929 (or 2538151921 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 40.

The spelling of 81220861408 in words is "eighty-one billion, two hundred twenty million, eight hundred sixty-one thousand, four hundred eight".