61988821 has 2 divisors, whose sum is σ = 61988822. Its totient is φ = 61988820.

The previous prime is 61988819. The next prime is 61988833. The reversal of 61988821 is 12888916.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59136100 + 2852721 = 7690^2 + 1689^2 .

It is a cyclic number.

It is not a de Polignac number, because 61988821 - 2¹ = 61988819 is a prime.

It is a super-2 number, since 2×61988821² = 7685227857940082, which contains 22 as substring.

Together with 61988819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61988891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30994410 + 30994411.

It is an arithmetic number, because the mean of its divisors is an integer number (30994411).

Almost surely, 2^61988821 is an apocalyptic number.

It is an amenable number.

61988821 is a deficient number, since it is larger than the sum of its proper divisors (1).

61988821 is an equidigital number, since it uses as much as digits as its factorization.

61988821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 43.

The square root of 61988821 is about 7873.2979748006. The cubic root of 61988821 is about 395.7653717585.

The spelling of 61988821 in words is "sixty-one million, nine hundred eighty-eight thousand, eight hundred twenty-one".