19856551990 has 32 divisors (see below), whose sum is σ = 41284642464. Its totient is φ = 6795824640.

The previous prime is 19856551969. The next prime is 19856551993. The reversal of 19856551990 is 9915565891.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19856551993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5307369 + ... + 5311108.

It is an arithmetic number, because the mean of its divisors is an integer number (1290145077).

Almost surely, 2^19856551990 is an apocalyptic number.

19856551990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19856551990 is an abundant number, since it is smaller than the sum of its proper divisors (21428090474).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19856551990 is a wasteful number, since it uses less digits than its factorization.

19856551990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10618512.

The product of its (nonzero) digits is 4374000, while the sum is 58.

The spelling of 19856551990 in words is "nineteen billion, eight hundred fifty-six million, five hundred fifty-one thousand, nine hundred ninety".