51251421 has 32 divisors (see below), whose sum is σ = 75866112. Its totient is φ = 30582720.

The previous prime is 51251419. The next prime is 51251437. The reversal of 51251421 is 12415215.

It is not a de Polignac number, because 51251421 - 2¹ = 51251419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51251411) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 229716 + ... + 229938.

It is an arithmetic number, because the mean of its divisors is an integer number (2370816).

Almost surely, 2^51251421 is an apocalyptic number.

It is an amenable number.

51251421 is a deficient number, since it is larger than the sum of its proper divisors (24614691).

51251421 is a wasteful number, since it uses less digits than its factorization.

51251421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393.

The product of its digits is 400, while the sum is 21.

The square root of 51251421 is about 7159.0097778953. The cubic root of 51251421 is about 371.4513750652.

Adding to 51251421 its reverse (12415215), we get a palindrome (63666636).

The spelling of 51251421 in words is "fifty-one million, two hundred fifty-one thousand, four hundred twenty-one".