645221797 has 8 divisors (see below), whose sum is σ = 721046592. Its totient is φ = 572258400.

The previous prime is 645221743. The next prime is 645221807. The reversal of 645221797 is 797122546.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645221797 is a prime.

It is a super-2 number, since 2×645221797² = 832622334647818418, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645221497) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 714873 + ... + 715774.

It is an arithmetic number, because the mean of its divisors is an integer number (90130824).

Almost surely, 2^645221797 is an apocalyptic number.

It is an amenable number.

645221797 is a deficient number, since it is larger than the sum of its proper divisors (75824795).

645221797 is a wasteful number, since it uses less digits than its factorization.

645221797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1430699.

The product of its digits is 211680, while the sum is 43.

The square root of 645221797 is about 25401.2164472491. The cubic root of 645221797 is about 864.1112847662. Note that the first 3 decimals are identical.

The spelling of 645221797 in words is "six hundred forty-five million, two hundred twenty-one thousand, seven hundred ninety-seven".