21253551031 has 4 divisors (see below), whose sum is σ = 22372159000. Its totient is φ = 20134943064.

The previous prime is 21253550953. The next prime is 21253551037. The reversal of 21253551031 is 13015535212.

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 21253551031 - 2¹⁷ = 21253419959 is a prime.

It is a super-2 number, since 2×21253551031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253551037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559303956 + ... + 559303993.

It is an arithmetic number, because the mean of its divisors is an integer number (5593039750).

Almost surely, 2^21253551031 is an apocalyptic number.

21253551031 is a deficient number, since it is larger than the sum of its proper divisors (1118607969).

21253551031 is a wasteful number, since it uses less digits than its factorization.

21253551031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1118607968.

The product of its (nonzero) digits is 4500, while the sum is 28.

The spelling of 21253551031 in words is "twenty-one billion, two hundred fifty-three million, five hundred fifty-one thousand, thirty-one".