19972991 has 8 divisors (see below), whose sum is σ = 20207040. Its totient is φ = 19740672.

The previous prime is 19972987. The next prime is 19973029. The reversal of 19972991 is 19927991.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 19972991 - 2² = 19972987 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 (19972951) 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, 45911 + ... + 46343.

It is an arithmetic number, because the mean of its divisors is an integer number (2525880).

Almost surely, 2^19972991 is an apocalyptic number.

19972991 is a deficient number, since it is larger than the sum of its proper divisors (234049).

19972991 is a wasteful number, since it uses less digits than its factorization.

19972991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 865.

The product of its digits is 91854, while the sum is 47.

The square root of 19972991 is about 4469.1152368226. The cubic root of 19972991 is about 271.3195171056.

The spelling of 19972991 in words is "nineteen million, nine hundred seventy-two thousand, nine hundred ninety-one".