745631021 has 2 divisors, whose sum is σ = 745631022. Its totient is φ = 745631020.

The previous prime is 745631017. The next prime is 745631023. The reversal of 745631021 is 120136547.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 569776900 + 175854121 = 23870^2 + 13261^2 .

It is an emirp because it is prime and its reverse (120136547) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 745631021 - 2² = 745631017 is a prime.

It is a Sophie Germain prime.

Together with 745631023, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (745631023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 372815510 + 372815511.

It is an arithmetic number, because the mean of its divisors is an integer number (372815511).

Almost surely, 2^745631021 is an apocalyptic number.

It is an amenable number.

745631021 is a deficient number, since it is larger than the sum of its proper divisors (1).

745631021 is an equidigital number, since it uses as much as digits as its factorization.

745631021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 745631021 is about 27306.2450915537. The cubic root of 745631021 is about 906.7926458783.

Adding to 745631021 its reverse (120136547), we get a palindrome (865767568).

The spelling of 745631021 in words is "seven hundred forty-five million, six hundred thirty-one thousand, twenty-one".