81561435 has 16 divisors (see below), whose sum is σ = 132961824. Its totient is φ = 42678272.

The previous prime is 81561421. The next prime is 81561457. The reversal of 81561435 is 53416518.

It is a cyclic number.

It is not a de Polignac number, because 81561435 - 2⁴ = 81561419 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81561396 and 81561405.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50502 + ... + 52091.

It is an arithmetic number, because the mean of its divisors is an integer number (8310114).

Almost surely, 2^81561435 is an apocalyptic number.

81561435 is a deficient number, since it is larger than the sum of its proper divisors (51400389).

81561435 is a wasteful number, since it uses less digits than its factorization.

81561435 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102654.

The product of its digits is 14400, while the sum is 33.

The square root of 81561435 is about 9031.1369716110. The cubic root of 81561435 is about 433.6722361955.

It can be divided in two parts, 8156 and 1435, that added together give a triangular number (9591 = T₁₃₈).

The spelling of 81561435 in words is "eighty-one million, five hundred sixty-one thousand, four hundred thirty-five".