19911631 has 2 divisors, whose sum is σ = 19911632. Its totient is φ = 19911630.

The previous prime is 19911599. The next prime is 19911643. The reversal of 19911631 is 13611991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19911631 - 2⁵ = 19911599 is a prime.

It is a super-2 number, since 2×19911631² = 792946098160322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19911593 and 19911602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19911431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9955815 + 9955816.

It is an arithmetic number, because the mean of its divisors is an integer number (9955816).

Almost surely, 2^19911631 is an apocalyptic number.

19911631 is a deficient number, since it is larger than the sum of its proper divisors (1).

19911631 is an equidigital number, since it uses as much as digits as its factorization.

19911631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1458, while the sum is 31.

The square root of 19911631 is about 4462.2450627459. The cubic root of 19911631 is about 271.0413874508.

The spelling of 19911631 in words is "nineteen million, nine hundred eleven thousand, six hundred thirty-one".