1621321951 has 2 divisors, whose sum is σ = 1621321952. Its totient is φ = 1621321950.

The previous prime is 1621321939. The next prime is 1621321963. The reversal of 1621321951 is 1591231261.

It is a balanced prime because it is at equal distance from previous prime (1621321939) and next prime (1621321963).

It is an emirp because it is prime and its reverse (1591231261) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1621321951 - 2⁹ = 1621321439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621321921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810660975 + 810660976.

It is an arithmetic number, because the mean of its divisors is an integer number (810660976).

Almost surely, 2^1621321951 is an apocalyptic number.

1621321951 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621321951 is an equidigital number, since it uses as much as digits as its factorization.

1621321951 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 31.

The square root of 1621321951 is about 40265.6423145093. The cubic root of 1621321951 is about 1174.7796661856.

The spelling of 1621321951 in words is "one billion, six hundred twenty-one million, three hundred twenty-one thousand, nine hundred fifty-one".