1921221291 has 32 divisors (see below), whose sum is σ = 2848317696. Its totient is φ = 1142064000.

The previous prime is 1921221277. The next prime is 1921221299.

1921221291 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1921221291 - 2¹¹ = 1921219243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1921221299) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 846340 + ... + 848606.

It is an arithmetic number, because the mean of its divisors is an integer number (89009928).

Almost surely, 2^1921221291 is an apocalyptic number.

1921221291 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1921221291 is a deficient number, since it is larger than the sum of its proper divisors (927096405).

1921221291 is a wasteful number, since it uses less digits than its factorization.

1921221291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2763.

The product of its digits is 1296, while the sum is 30.

The square root of 1921221291 is about 43831.7383981060. The cubic root of 1921221291 is about 1243.1564767399.

The spelling of 1921221291 in words is "one billion, nine hundred twenty-one million, two hundred twenty-one thousand, two hundred ninety-one".