64401521 has 2 divisors, whose sum is σ = 64401522. Its totient is φ = 64401520.

The previous prime is 64401517. The next prime is 64401523. The reversal of 64401521 is 12510446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54390625 + 10010896 = 7375^2 + 3164^2 .

It is a cyclic number.

It is not a de Polignac number, because 64401521 - 2² = 64401517 is a prime.

It is a super-2 number, since 2×64401521² = 8295111814226882, which contains 22 as substring.

Together with 64401523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (64401523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32200760 + 32200761.

It is an arithmetic number, because the mean of its divisors is an integer number (32200761).

Almost surely, 2^64401521 is an apocalyptic number.

It is an amenable number.

64401521 is a deficient number, since it is larger than the sum of its proper divisors (1).

64401521 is an equidigital number, since it uses as much as digits as its factorization.

64401521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 64401521 is about 8025.0558253510. The cubic root of 64401521 is about 400.8347588158.

Adding to 64401521 its reverse (12510446), we get a palindrome (76911967).

The spelling of 64401521 in words is "sixty-four million, four hundred one thousand, five hundred twenty-one".