81622745261 has 4 divisors (see below), whose sum is σ = 81669468672. Its totient is φ = 81576021852.

The previous prime is 81622745231. The next prime is 81622745263. The reversal of 81622745261 is 16254722618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81622745261 - 2²⁶ = 81555636397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81622745263) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23359085 + ... + 23362578.

It is an arithmetic number, because the mean of its divisors is an integer number (20417367168).

Almost surely, 2^81622745261 is an apocalyptic number.

It is an amenable number.

81622745261 is a deficient number, since it is larger than the sum of its proper divisors (46723411).

81622745261 is a wasteful number, since it uses less digits than its factorization.

81622745261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46723410.

The product of its digits is 322560, while the sum is 44.

The spelling of 81622745261 in words is "eighty-one billion, six hundred twenty-two million, seven hundred forty-five thousand, two hundred sixty-one".