81219651 has 8 divisors (see below), whose sum is σ = 108743184. Its totient is φ = 53921280.

The previous prime is 81219643. The next prime is 81219653. The reversal of 81219651 is 15691218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81219651 - 2³ = 81219643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81219653) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55446 + ... + 56891.

It is an arithmetic number, because the mean of its divisors is an integer number (13592898).

Almost surely, 2^81219651 is an apocalyptic number.

81219651 is a deficient number, since it is larger than the sum of its proper divisors (27523533).

81219651 is a wasteful number, since it uses less digits than its factorization.

81219651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112581.

The product of its digits is 4320, while the sum is 33.

The square root of 81219651 is about 9012.1945718010. The cubic root of 81219651 is about 433.0656187944.

The spelling of 81219651 in words is "eighty-one million, two hundred nineteen thousand, six hundred fifty-one".