19811211890 has 16 divisors (see below), whose sum is σ = 36529942680. Its totient is φ = 7731204480.

The previous prime is 19811211857. The next prime is 19811211907. The reversal of 19811211890 is 9811211891.

It can be written as a sum of positive squares in 4 ways, for example, as 7617972961 + 12193238929 = 87281^2 + 110423^2 .

It is a Harshad number since it is a multiple of its sum of digits (41).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24159605 + ... + 24160424.

Almost surely, 2^19811211890 is an apocalyptic number.

19811211890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19811211890 is a deficient number, since it is larger than the sum of its proper divisors (16718730790).

19811211890 is a wasteful number, since it uses less digits than its factorization.

19811211890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48320077.

The product of its (nonzero) digits is 10368, while the sum is 41.

Subtracting from 19811211890 its reverse (9811211891), we obtain a palindrome (9999999999).

The spelling of 19811211890 in words is "nineteen billion, eight hundred eleven million, two hundred eleven thousand, eight hundred ninety".