61221521 has 2 divisors, whose sum is σ = 61221522. Its totient is φ = 61221520.

The previous prime is 61221473. The next prime is 61221529. The reversal of 61221521 is 12512216.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37650496 + 23571025 = 6136^2 + 4855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61221521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 61221493 and 61221502.

It is not a weakly prime, because it can be changed into another prime (61221529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30610760 + 30610761.

It is an arithmetic number, because the mean of its divisors is an integer number (30610761).

Almost surely, 2^61221521 is an apocalyptic number.

It is an amenable number.

61221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

61221521 is an equidigital number, since it uses as much as digits as its factorization.

61221521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 240, while the sum is 20.

The square root of 61221521 is about 7824.4182531355. The cubic root of 61221521 is about 394.1256545632.

Adding to 61221521 its reverse (12512216), we get a palindrome (73733737).

The spelling of 61221521 in words is "sixty-one million, two hundred twenty-one thousand, five hundred twenty-one".