1021505491 has 2 divisors, whose sum is σ = 1021505492. Its totient is φ = 1021505490.

The previous prime is 1021505489. The next prime is 1021505533. The reversal of 1021505491 is 1945051201.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1021505491 - 2¹ = 1021505489 is a prime.

Together with 1021505489, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1021505461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510752745 + 510752746.

It is an arithmetic number, because the mean of its divisors is an integer number (510752746).

Almost surely, 2^1021505491 is an apocalyptic number.

1021505491 is a deficient number, since it is larger than the sum of its proper divisors (1).

1021505491 is an equidigital number, since it uses as much as digits as its factorization.

1021505491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1800, while the sum is 28.

The square root of 1021505491 is about 31960.9995306780. Note that the first 3 decimals coincide. The cubic root of 1021505491 is about 1007.1177149352.

Adding to 1021505491 its reverse (1945051201), we get a palindrome (2966556692).

The spelling of 1021505491 in words is "one billion, twenty-one million, five hundred five thousand, four hundred ninety-one".