21891770731 has 4 divisors (see below), whose sum is σ = 21892947264. Its totient is φ = 21890594200.

The previous prime is 21891770717. The next prime is 21891770741. The reversal of 21891770731 is 13707719812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21891770731 - 2¹⁵ = 21891737963 is a prime.

It is a super-2 number, since 2×21891770731² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21891770741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559900 + ... + 597721.

It is an arithmetic number, because the mean of its divisors is an integer number (5473236816).

Almost surely, 2^21891770731 is an apocalyptic number.

21891770731 is a deficient number, since it is larger than the sum of its proper divisors (1176533).

21891770731 is a wasteful number, since it uses less digits than its factorization.

21891770731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1176532.

The product of its (nonzero) digits is 148176, while the sum is 46.

The spelling of 21891770731 in words is "twenty-one billion, eight hundred ninety-one million, seven hundred seventy thousand, seven hundred thirty-one".