1251321021 has 8 divisors (see below), whose sum is σ = 1853808960. Its totient is φ = 834213996.

The previous prime is 1251320977. The next prime is 1251321037. The reversal of 1251321021 is 1201231521.

It is not a de Polignac number, because 1251321021 - 2⁷ = 1251320893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1251320985 and 1251321003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251321061) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23172585 + ... + 23172638.

It is an arithmetic number, because the mean of its divisors is an integer number (231726120).

Almost surely, 2^1251321021 is an apocalyptic number.

It is an amenable number.

1251321021 is a deficient number, since it is larger than the sum of its proper divisors (602487939).

1251321021 is an equidigital number, since it uses as much as digits as its factorization.

1251321021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46345232 (or 46345226 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 1251321021 is about 35374.0161841994. The cubic root of 1251321021 is about 1077.5966852121.

Adding to 1251321021 its reverse (1201231521), we get a palindrome (2452552542).

The spelling of 1251321021 in words is "one billion, two hundred fifty-one million, three hundred twenty-one thousand, twenty-one".