1351664021 has 4 divisors (see below), whose sum is σ = 1383098112. Its totient is φ = 1320229932.

The previous prime is 1351663997. The next prime is 1351664059. The reversal of 1351664021 is 1204661531.

It is a happy number.

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 cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1351664021 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 (1351664071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15716981 + ... + 15717066.

It is an arithmetic number, because the mean of its divisors is an integer number (345774528).

Almost surely, 2^1351664021 is an apocalyptic number.

It is an amenable number.

1351664021 is a deficient number, since it is larger than the sum of its proper divisors (31434091).

1351664021 is an equidigital number, since it uses as much as digits as its factorization.

1351664021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31434090.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 1351664021 is about 36764.9836257273. The cubic root of 1351664021 is about 1105.6633598697.

The spelling of 1351664021 in words is "one billion, three hundred fifty-one million, six hundred sixty-four thousand, twenty-one".