81455651 has 2 divisors, whose sum is σ = 81455652. Its totient is φ = 81455650.

The previous prime is 81455623. The next prime is 81455657. The reversal of 81455651 is 15655418.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81455651 - 2¹⁰ = 81454627 is a prime.

It is not a weakly prime, because it can be changed into another prime (81455657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40727825 + 40727826.

It is an arithmetic number, because the mean of its divisors is an integer number (40727826).

Almost surely, 2^81455651 is an apocalyptic number.

81455651 is a deficient number, since it is larger than the sum of its proper divisors (1).

81455651 is an equidigital number, since it uses as much as digits as its factorization.

81455651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24000, while the sum is 35.

The square root of 81455651 is about 9025.2784444581. The cubic root of 81455651 is about 433.4846662103.

It can be divided in two parts, 814 and 55651, that added together give a palindrome (56465).

The spelling of 81455651 in words is "eighty-one million, four hundred fifty-five thousand, six hundred fifty-one".