72999991 has 2 divisors, whose sum is σ = 72999992. Its totient is φ = 72999990.

The previous prime is 72999973. The next prime is 73000003. The reversal of 72999991 is 19999927.

It is a strong prime.

It is an emirp because it is prime and its reverse (19999927) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72999991 - 2¹⁹ = 72475703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72999961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36499995 + 36499996.

It is an arithmetic number, because the mean of its divisors is an integer number (36499996).

Almost surely, 2^72999991 is an apocalyptic number.

72999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

72999991 is an equidigital number, since it uses as much as digits as its factorization.

72999991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 826686, while the sum is 55.

The square root of 72999991 is about 8544.0032186324. The cubic root of 72999991 is about 417.9339024628.

Subtracting from 72999991 its sum of digits (55), we obtain a square (72999936 = 8544²).

The spelling of 72999991 in words is "seventy-two million, nine hundred ninety-nine thousand, nine hundred ninety-one".