21623734 has 16 divisors (see below), whose sum is σ = 36605520. Its totient is φ = 9489760.

The previous prime is 21623731. The next prime is 21623773. The reversal of 21623734 is 43732612.

21623734 = T₁₉₇ + T₁₉₈ + ... + T₅₁₅.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623731) 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, 16309 + ... + 17584.

It is an arithmetic number, because the mean of its divisors is an integer number (2287845).

Almost surely, 2^21623734 is an apocalyptic number.

21623734 is a deficient number, since it is larger than the sum of its proper divisors (14981786).

21623734 is a wasteful number, since it uses less digits than its factorization.

21623734 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33935.

The product of its digits is 6048, while the sum is 28.

The square root of 21623734 is about 4650.1326862790. The cubic root of 21623734 is about 278.5972958917.

The spelling of 21623734 in words is "twenty-one million, six hundred twenty-three thousand, seven hundred thirty-four".