21251231070 has 32 divisors (see below), whose sum is σ = 51030701568. Its totient is φ = 5663911968.

The previous prime is 21251231047. The next prime is 21251231077. The reversal of 21251231070 is 7013215212.

It is a super-2 number, since 2×21251231070² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21251231070.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251231077) 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, 136354 + ... + 247173.

It is an arithmetic number, because the mean of its divisors is an integer number (1594709424).

Almost surely, 2^21251231070 is an apocalyptic number.

21251231070 is an abundant number, since it is smaller than the sum of its proper divisors (29779470498).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21251231070 is a wasteful number, since it uses less digits than its factorization.

21251231070 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 385384.

The product of its (nonzero) digits is 840, while the sum is 24.

Adding to 21251231070 its reverse (7013215212), we get a palindrome (28264446282).

The spelling of 21251231070 in words is "twenty-one billion, two hundred fifty-one million, two hundred thirty-one thousand, seventy".