1990281821 has 16 divisors (see below), whose sum is σ = 2197324800. Its totient is φ = 1787713200.

The previous prime is 1990281791. The next prime is 1990281829. The reversal of 1990281821 is 1281820991.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1990281821 is a prime.

It is a super-2 number, since 2×1990281821² = 7922443454006152082, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1990281829) 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, 341510 + ... + 347288.

It is an arithmetic number, because the mean of its divisors is an integer number (137332800).

Almost surely, 2^1990281821 is an apocalyptic number.

1990281821 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1990281821 is a deficient number, since it is larger than the sum of its proper divisors (207042979).

1990281821 is a wasteful number, since it uses less digits than its factorization.

1990281821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6160.

The product of its (nonzero) digits is 20736, while the sum is 41.

The square root of 1990281821 is about 44612.5746959307. The cubic root of 1990281821 is about 1257.8770459305.

The spelling of 1990281821 in words is "one billion, nine hundred ninety million, two hundred eighty-one thousand, eight hundred twenty-one".