51642421 has 2 divisors, whose sum is σ = 51642422. Its totient is φ = 51642420.

The previous prime is 51642419. The next prime is 51642431. The reversal of 51642421 is 12424615.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45037521 + 6604900 = 6711^2 + 2570^2 .

It is a cyclic number.

It is not a de Polignac number, because 51642421 - 2¹ = 51642419 is a prime.

Together with 51642419, 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 (51642401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25821210 + 25821211.

It is an arithmetic number, because the mean of its divisors is an integer number (25821211).

Almost surely, 2^51642421 is an apocalyptic number.

It is an amenable number.

51642421 is a deficient number, since it is larger than the sum of its proper divisors (1).

51642421 is an equidigital number, since it uses as much as digits as its factorization.

51642421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1920, while the sum is 25.

The square root of 51642421 is about 7186.2661375710. The cubic root of 51642421 is about 372.3935909142.

The spelling of 51642421 in words is "fifty-one million, six hundred forty-two thousand, four hundred twenty-one".