64021997251 has 16 divisors (see below), whose sum is σ = 66095656704. Its totient is φ = 61977119904.

The previous prime is 64021997239. The next prime is 64021997269. The reversal of 64021997251 is 15279912046.

It is a cyclic number.

It is not a de Polignac number, because 64021997251 - 2³⁵ = 29662258883 is a prime.

It is a super-2 number, since 2×64021997251² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (64021997551) 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, 2478961 + ... + 2504653.

It is an arithmetic number, because the mean of its divisors is an integer number (4130978544).

Almost surely, 2^64021997251 is an apocalyptic number.

64021997251 is a deficient number, since it is larger than the sum of its proper divisors (2073659453).

64021997251 is a wasteful number, since it uses less digits than its factorization.

64021997251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26250.

The product of its (nonzero) digits is 272160, while the sum is 46.

The spelling of 64021997251 in words is "sixty-four billion, twenty-one million, nine hundred ninety-seven thousand, two hundred fifty-one".