1951721 has 2 divisors, whose sum is σ = 1951722. Its totient is φ = 1951720.

The previous prime is 1951709. The next prime is 1951739. The reversal of 1951721 is 1271591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1597696 + 354025 = 1264^2 + 595^2 .

It is a cyclic number.

It is not a de Polignac number, because 1951721 - 2⁶ = 1951657 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p₁₄₅₆₁₉ and since 1951721 and 145619 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (1951321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 975860 + 975861.

It is an arithmetic number, because the mean of its divisors is an integer number (975861).

2^1951721 is an apocalyptic number.

It is an amenable number.

1951721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1951721 is an equidigital number, since it uses as much as digits as its factorization.

1951721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 630, while the sum is 26.

The square root of 1951721 is about 1397.0400853233. The cubic root of 1951721 is about 124.9700408202.

The spelling of 1951721 in words is "one million, nine hundred fifty-one thousand, seven hundred twenty-one".