1621531357 has 2 divisors, whose sum is σ = 1621531358. Its totient is φ = 1621531356.

The previous prime is 1621531339. The next prime is 1621531391. The reversal of 1621531357 is 7531351261.

It is an a-pointer prime, because the next prime (1621531391) can be obtained adding 1621531357 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1607288281 + 14243076 = 40091^2 + 3774^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1621531357 is a prime.

It is a super-2 number, since 2×1621531357² = 5258727883468522898, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621531957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810765678 + 810765679.

It is an arithmetic number, because the mean of its divisors is an integer number (810765679).

Almost surely, 2^1621531357 is an apocalyptic number.

It is an amenable number.

1621531357 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621531357 is an equidigital number, since it uses as much as digits as its factorization.

1621531357 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18900, while the sum is 34.

The square root of 1621531357 is about 40268.2425367684. The cubic root of 1621531357 is about 1174.8302412365.

The spelling of 1621531357 in words is "one billion, six hundred twenty-one million, five hundred thirty-one thousand, three hundred fifty-seven".