51621551 has 2 divisors, whose sum is σ = 51621552. Its totient is φ = 51621550.

The previous prime is 51621539. The next prime is 51621553. The reversal of 51621551 is 15512615.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51621551 is a prime.

Together with 51621553, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51621551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51621553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25810775 + 25810776.

It is an arithmetic number, because the mean of its divisors is an integer number (25810776).

Almost surely, 2^51621551 is an apocalyptic number.

51621551 is a deficient number, since it is larger than the sum of its proper divisors (1).

51621551 is an equidigital number, since it uses as much as digits as its factorization.

51621551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1500, while the sum is 26.

The square root of 51621551 is about 7184.8139154748. The cubic root of 51621551 is about 372.3434196192.

The spelling of 51621551 in words is "fifty-one million, six hundred twenty-one thousand, five hundred fifty-one".