51991049 has 16 divisors (see below), whose sum is σ = 63218880. Its totient is φ = 42140160.

The previous prime is 51991007. The next prime is 51991081. The reversal of 51991049 is 94019915.

It is a cyclic number.

It is not a de Polignac number, because 51991049 - 2⁸ = 51990793 is a prime.

It is a super-2 number, since 2×51991049² = 5406138352240802, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51991249) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3764 + ... + 10869.

It is an arithmetic number, because the mean of its divisors is an integer number (3951180).

Almost surely, 2^51991049 is an apocalyptic number.

It is an amenable number.

51991049 is a deficient number, since it is larger than the sum of its proper divisors (11227831).

51991049 is a wasteful number, since it uses less digits than its factorization.

51991049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14680.

The product of its (nonzero) digits is 14580, while the sum is 38.

The square root of 51991049 is about 7210.4818840352. The cubic root of 51991049 is about 373.2296979737.

The spelling of 51991049 in words is "fifty-one million, nine hundred ninety-one thousand, forty-nine".