1021665397 has 4 divisors (see below), whose sum is σ = 1075437280. Its totient is φ = 967893516.

The previous prime is 1021665383. The next prime is 1021665413. The reversal of 1021665397 is 7935661201.

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 a de Polignac number, because none of the positive numbers 2^k-1021665397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1021665797) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26885913 + ... + 26885950.

It is an arithmetic number, because the mean of its divisors is an integer number (268859320).

Almost surely, 2^1021665397 is an apocalyptic number.

It is an amenable number.

1021665397 is a deficient number, since it is larger than the sum of its proper divisors (53771883).

1021665397 is an equidigital number, since it uses as much as digits as its factorization.

1021665397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53771882.

The product of its (nonzero) digits is 68040, while the sum is 40.

The square root of 1021665397 is about 31963.5010128740. The cubic root of 1021665397 is about 1007.1702634414.

The spelling of 1021665397 in words is "one billion, twenty-one million, six hundred sixty-five thousand, three hundred ninety-seven".