1021491381 has 4 divisors (see below), whose sum is σ = 1361988512. Its totient is φ = 680994252.

The previous prime is 1021491377. The next prime is 1021491391. The reversal of 1021491381 is 1831941201.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 1021491381 - 2² = 1021491377 is a prime.

It is a super-2 number, since 2×1021491381² = 2086889282914574322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021491311) 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 in 3 ways as a sum of consecutive naturals, for example, 170248561 + ... + 170248566.

It is an arithmetic number, because the mean of its divisors is an integer number (340497128).

Almost surely, 2^1021491381 is an apocalyptic number.

It is an amenable number.

1021491381 is a deficient number, since it is larger than the sum of its proper divisors (340497131).

1021491381 is an equidigital number, since it uses as much as digits as its factorization.

1021491381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340497130.

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 1021491381 is about 31960.7787921383. The cubic root of 1021491381 is about 1007.1130778264.

The spelling of 1021491381 in words is "one billion, twenty-one million, four hundred ninety-one thousand, three hundred eighty-one".