72821237691 has 4 divisors (see below), whose sum is σ = 97094983592. Its totient is φ = 48547491792.

The previous prime is 72821237651. The next prime is 72821237693. The reversal of 72821237691 is 19673212827.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 72821237691 - 2¹⁸ = 72820975547 is a prime.

It is a super-2 number, since 2×72821237691² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72821237691.

It is not an unprimeable number, because it can be changed into a prime (72821237693) 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, 12136872946 + ... + 12136872951.

It is an arithmetic number, because the mean of its divisors is an integer number (24273745898).

Almost surely, 2^72821237691 is an apocalyptic number.

72821237691 is a deficient number, since it is larger than the sum of its proper divisors (24273745901).

72821237691 is a wasteful number, since it uses less digits than its factorization.

72821237691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24273745900.

The product of its digits is 508032, while the sum is 48.

The spelling of 72821237691 in words is "seventy-two billion, eight hundred twenty-one million, two hundred thirty-seven thousand, six hundred ninety-one".